It's a big balancing act.

Sure. And the younger you are when you retire, the greater the risk you might be forced to go back to work or come up with some other source of income.

Similarly, you may have to be conservative in the early days, but as you grow older and the risk becomes more manageable, "spend it down" becomes more attractive.

Once you retire, go through a stock market "adjustment" and survive, your confidence in your numbers grows. And you become more comfortable with the risks.

But similarly, some of the expenses are likely to be greater than what you planned for. In my case, the big surprise was the cost increase of health insurance. But having made it to Social Security age and now Medicare, the worries are much reduced.

As always, your mileage may vary. But things can still work out.

If in doubt, work an extra year and build yourself a bit more of a reserve.