If you wait too long to start spending your money, you will have wasted many years of unnecessary work, stress, and worry. You'll have traded your best decades for a number on a screen that eventually gets passed to someone else.

After another summer living with my parents, I'm even more convinced about 45, my recommended start of decumulation. Not because the math changed, but because I watched the alternative up close for two summers in a row.

Here's the realization: you won't be able to spend all your money when you're old. Not “you shouldn't.” You won't be able to. The ability and the desire itself disappears.

And when I say old, I'll peg that age at 65+, the traditional retirement age when corporations no longer deem you productive enough to keep around.

The Inability To Spend Money When You're Old

If you want to get a glimpse of how you'll be when you're old, simply spend more time with your parents when they're old.…