A few weeks ago, I ran into a 67-year-old neighbor. He had just retired after spending 42 years with a Fortune 500 company. But it turned out congratulations were not in order.

He didn't want to retire. He liked his job. He liked the people he worked with. He liked the sense of purpose, meaning, and belonging.

Yet while age discrimination laws leave the decision of when to retire up to the employee, there are ways around that; his employer had made it humiliatingly clear it was time for him to go. 

I felt bad for him.

Later that day, I broke a tooth (getting old sucks). I called my dentist. He said they would squeeze me in.

As I sat down in the chair, he walked into the room, literally rubbed his gloved hands together, and exclaimed, "Ha ha! What fine challenge have you brought me to solve today?" 

Even though I hate going to the dentist -- I like my dentist, but I hate everything about having my teeth worked on -- I had to smile.

For him, the bigger the reconstructive challenge, the better. Five decades in, he still loves being a dentist.

Yep, he's 83. 

And still working.

Granted, he only works four days a week. Partly that's to give his staff more days off, but also because then he can spend Fridays volunteering at a free clinic. 

Why hasn't he retired? He doesn't want to. And as an entrepreneur, he doesn't have to. He gets to decide when it's time to leave, or stay. 

So he stays. Because he loves to work. Because he loves the work. Because his long-past-retirement-age receptionist depends on the income her job provides. 

Because being a dentist isn't what he does. Being a dentist is who he is, in the best possible way.

Yet he knows Father Time is undefeated, so he watches for the signs. Someday his eye-hand coordination will diminish. Someday his mental sharpness will drop. Someday the challenge of reconstructing the broken tooth between a capped root canal and a bridge will be more than he can handle.

But that day, as Aragorn would say, is not this day.

Because he, unlike my neighbor, gets to decide when that day comes. 

Sure, being an entrepreneur means being your own boss. Being an entrepreneur also means your income is potentially unlimited, rather than capped.

But being an entrepreneur also means you get to decide when you want to walk away. Or work fewer hours. Or spend a portion of your time on other pursuits. No one can tell you to leave -- or, at a certain age, put you in positions that eventually make you want to leave.

For many employees, retirement means leaving a job they no longer, if they ever really did, want to do. Retirement is a positive, but mostly because it means they finally get to escape a negative.

For many entrepreneurs though, retirement isn't something they look forward to. Retiring would mean leaving a job, and a life, they love. 

He works because he wants to.

When you love what you do, and how it fits into your life, the last thing you want is for someone to make you stop.

Because it's your life, and you should -- for as long as your skills permit -- be able to live it your way.