There are plenty of good reasons to not take Social Security at 62. The biggest one is that if you can wait until 70, you’ll get a much bigger monthly benefit.

But some folks can’t wait. They either need that guaranteed income now or certainly won’t make it to their eighth decade.

Here are the three top reasons for taking the “early” retirement benefit from Social Security:

* You’re chronically or terminally ill. We pray for a long and healthy life. But thousands are suffering from heart disease, cancer, diabetes or a range of conditions that will shorten their lives. We always hope the doctors are wrong. In that case, keep in mind that Social Security is a lifetime benefit, although locked in at a relatively low rate if you retire at 62. If you want wait to “normal” retirement age — 66 for most Americans — you’ll get a higher benefit.

* You have other savings. This is a big plus for early retirees. Many have taken the low-hanging fruit of reducing their expenses, total debt and don’t live high on the hog. They may have a steady pension or built up a solid nest egg. They are in the best position to leave the workforce at 62.

* You Can’t Continue in the Job or Industry You’re In. Some jobs or trades are so physically and mentally demanding that they wear people out. And it’s little consolation from self-help experts who insist that you “re-invent yourself” in your seventh decade. If you can retrain and re-educate yourself for a solid, good-paying trade or profession, I’m all for it, although it’s awfully hard to switch gears.

How much is enough to retire with dignity? See what payment you’re entitled to from Social Security based on your lifetime work credits. Then tally up your other savings. Estimate your ongoing living expenses, then do the math. This is the final equation, which works pretty well — even if you choose to wait to retire.