Fritz Gilbert knew in his 20s that he did not want to die at his desk.

Gilbert, 55, who retired last week, started saving decades ago for what could be one of our most fraught decisions: When to retire?

The question is deeply personal. It requires a brutal look at your life.

Some people get a pit in the stomach when they think about saying goodbye to that paycheck. Or at the prospect of deconstructing a nest egg they spent decades building. They might worry about feeling irrelevant or bored without the stimulation of work.

For most people, retirement won’t be carefree. They will replace whatever worries they have now with a new set of concerns: health (and their mortality), money, humankind’s future.

Of course, timing is everything: Retire too early and you risk outliving your money. Stay at the desk too long and you might miss out on life.

“Every one of us is making a decision on retirement every day, in the way we live and spend our money,” Gilbert said. “Not making a decision is still making a decision. Spend the money to buy that ‘thing,’ and you’ve made a decision to work longer.”

Regardless of whether they are ready to stop working, most Americans have not planned for retirement. Baby boomers – those born between 1946 and 1964 – have a median nest egg of $164,000. (Gen Xers and millennials have even less but more time to make it up.)

Many boomers are set to enter old age with whatever they have in Social Security and a few bucks.

And whether they have a lot of money or a little, “people are too nervous to pull the trigger and retire,” Washington financial adviser Lori Atwood said.

But you need to figure it out, she says. Otherwise, “you could be chained to your desk forever.”

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Think of retirement as a seesaw with four pails on one side labeled “assets” and four pails on the other marked “expenses.”

Assets include pensions/annuities, Social Security, investments, and inheritance and salary or wages if you plan on working. On the outgoing side are daily living expenses, health care, long-term care and fun stuff like travel and philanthropy.

The trick is keeping them balanced.

Gilbert is a case study on how to mentally and financially ready yourself to retire. He saved like mad, maximized tax-deferred retirement accounts and created a diversified portfolio of low-cost mutual funds. He lived well but prudently.

When he started in the aluminum business at a $21,500 salary in 1985, Gilbert knew that he wanted financial independence.

He and his wife banked every cent she earned as an administrative assistant until she became a stay-at-home-mom when their daughter was born in 1994.

There were modest vacations. Nothing crazy. He put his paycheck on autopilot, paying into his 401(k) before he spent a cent.

“I probably saved 20 to 25 percent of my income,” said Gilbert, who earned six-figures by the time he retired.

Saving early is everything – but it’s never too late to start.

Atwood tells clients 55 and older who haven’t prepared for life after work to “start cutting some expenses and save like crazy.”

Do something, she says, because “dying at your desk is not a retirement plan.”

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Gilbert said 33 years of packing the maximum allowed into his 401(k) have paid off. He put most of the money in the stock market and then sat back and watched it grow over decades.

“I am a 401(k) millionaire,” he said.

He keeps three years of living expenses in cash. The rest of his investments are split between 60 percent stocks and 40 percent bonds, consistent with the playbook that most financial experts recommend for someone in his 50s and 60s.

“Somewhere between 40 percent to 60 percent equities is a great place for most folks entering retirement age,” said David Blanchett, head of retirement research at Morningstar Investment Management. But you can even get riskier. “Assuming retirement is going to last 30 years, I think 70/30 stocks to bonds could be more aggressive.”

Wade Pfau, an economist with McLean Asset Management, proposes a counterpoint. Pfau said investors at or near retirement should be more conservative so they can manage a market crash or economic downturn that could obliterate their nest egg and force them to keep working.

Pfau said one solution is to lower one’s stock allocation by purchasing annuities, which guarantee a stream of income. Those stocks should grow in value as a proportion of one’s portfolio, creating what Pfau calls in a research paper a “rising glide path.”

“You are most exposed to market risk around the retirement date,” Pfau said. “As a risk-management technique, that’s when you want the lowest stock allocation. You can increase your stock allocation later.”

That strategy has its own risks.

“Being conservative is as dangerous as being too aggressive,” Blanchett said.

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One key to escaping workdom is a rare, golden asset: a pension.

“The best way to hedge against the fear of outliving your savings is through some form of guaranteed income,” Blanchett said.

Pensions and other fixed income – Social Security, bonds, annuities – create security but they also open up options. Recipients can become more aggressive with their investments, waiting out any downturns and putting more money into high-growth stocks.

Nancy Schlossberg, a former professor who has written extensively on retirement, said the pension she collects from 30 years teaching at the University of Maryland cushioned the transition.

More and more employers have transferred the burden of funding pensions – known as defined benefit plans – off their own balance sheets and onto employees through 401(k), 403(b) or other tax-deferred devices, known as defined contribution plans.

Employers prefer defined contribution plans because they are not legally bound to guarantee a pension check to retirees.

“You don’t have people like me anymore,” Schlossberg said.

Most boomers are banking on Social Security, but not all of them.

With his trifecta of having a pension, healthy investments and a corporate board seat that pays a fee, Gilbert is in the enviable position of delaying Social Security until age 70.

If he takes it at 62, his monthly Social Security check would be $2,060. By waiting until he is 70, it would grow to $3,643.

Many experts thinks that’s wise, especially if you are in good health and stand to live into your 80s and beyond.

Every year a person puts off collecting her Social Security benefits, her monthly check could increase by up to 8 percent, which is an equity-like return.

“People are living longer, and the benefits are guaranteed, tied to inflation and they are taxed favorably,” Blanchett said.

Not everyone has the luxury of waiting.

Take Steve Fischer, 66, a bed builder and 20-plus-year employee at Gat Creek Furniture, a factory in Berkeley Springs, West Virginia.

Fischer already collects Social Security to augment the $30,000 a year he earns at the factory. His wife and son also work at Gat Creek.

Fischer said he must work to provide for his family and to help support four grandchildren. He regrets that he didn’t save more for retirement.

“I didn’t look at the future,” Fischer said. He bought a home. “We lived from day to day.”

“I don’t mind working,” he said. “Probably work another year or so. I have a lot of projects around the house.”

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Big paycheck or small, many people find themselves getting the yips when it comes to pushing away from the desk.

“I talk about the income withdrawal syndrome,” Schlossberg said. “There is a fear element. You can get very scared and unsettled.”

Some are serial savers who can’t stand the idea of liquidating their fortune. And others are simply unsure how much money they’ll need.

“Not until clients get over $10 million in net worth do they really feel wealthy,” said Clark Kendall, a financial adviser in Montgomery County. “Even people with $3 million wonder, ‘Is it really enough to retire?’ ”

“People have no idea what the right number is,” Atwood says, “and the fact is, there is no right number. It depends on whether you have a mortgage and how much you need each month.”

And even if it is enough, there’s this: How do you draw down the money you’ve so carefully built up?

“There is a fundamental shift in your mind-set when you go into retirement,” Pfau said. “You are taking distributions from your assets rather than making contributions. That has a psychological impact. It’s completely different from what you’ve been doing your whole life.”

There are loads of ways to draw down your portfolio, including with annuities, bond laddering and simply selling off financial assets piecemeal.

Gilbert said his plan is to withdraw about 3 percent – or slightly more – from his portfolio annually. The financial community has long advocated a 4 percent annual withdrawal rate, assuming a 25-year or longer retirement.

Gilbert has reduced his living expenses: He has zero debt. He and his wife paid cash for their cars (Gilbert recently bought a Ford F250 pickup truck). He sold his 4,000-square-foot home in Atlanta, pocketing $460,000 after fees. They paid cash for a $200,000 cabin in the Appalachians. He cut his property tax by more than half.

“I call it geoarbitrage,” Gilbert said. “It’s moving to a lower cost of living for retirement to allow retirement funds to stretch further.”

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The X Factor, of course, is your health. Gilbert and his wife will buy private insurance until they are eligible for Medicare a decade from now.

Gilbert has budgeted $25,000 a year with built-in increases of 5 percent annually. They are able to buy his employer’s plan for the next 18 months under the government’s COBRA law.

Then, however, they will have to go into the open market and shop for insurance.

“We just hope and pray that we can find insurance for $25,000 a year,” he said.

Long-term care is another X Factor. It haunts boomers like John Atkocaitis, whose mother vaporized her nest egg.

“My mom was director of nursing and had a stroke at 61. She spent many of the next 15 years in a nursing home. It exhausted her assets,” said the 70-year-old publishing executive who is retiring this year. “We bought long-term care insurance probably 12 or 15 years ago, and I’m glad we did.”

Long-term care can be very expensive and bought either in a lump sum or in installments, or premiums.

The Gilberts elected to self-insure.

“Option B was to take the money we would have used to buy long-term care and invest it,” Gilbert said. “We assumed we wouldn’t need long-term care until our mid-80s. We may be wrong and the risk may bite us.”

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Family is one big reason people keep working.

Take Tom Boylan, 67, a Washington dentist who is financially fit but wants to leave enough for his grandchildren, which number 14 to date.

“They are going to need help,” he said.

Boylan took a hit like everyone else during the Great Recession. He sold a Florida real estate investment at a six-figure loss. His investment portfolio declined 35 percent.

But he stayed the course, kept his money in stocks and made it back and more in the current bull market.

He sold his dental practice but plans to stay on until age 70 or beyond.

He works about 65 percent of the time, but that may drop to just a couple of months a year.

“I joined a club down in Florida, so I have beer money to pay for that,” said the father of four. “Dentistry gives me some purpose. I love golf. I love tennis. But could I do that every day? No. Now I want to build that nest egg back up and help the kids get going.”

Gilbert is cruising into an affordable retirement that includes camping in national parks, fly-fishing, mountain biking, kayaking and his favorite – cold-water, long-distance swimming.

He even checked the philanthropy box. The Gilberts funded a Vanguard charitable trust last December with a mid-five-figure donation that gave them an immediate tax deduction. They can recommend grants to their favorite charities for the next five years.

Then there are those chained to their jobs for years to come. They’ll need luck, too. Luck that their job doesn’t go the way of toll-takers, bookstore employees, cashiers, coal miners, travel agents and even print journalists.

And let’s face it. Some people just love to work.

“What would I do if I retired?” asked Mark Feinsot, a 72-year-old certified public accountant in Manhattan. “I can’t imagine not having a place to go to in the morning. I will be carried out feet first.”