What didn't they tell you about aging?

Nobody told me that at some point after age 50, my nights of solid sleep would become nights of interruptions of one kind or another. There’s getting up to pee and a sort of in-and-out of sleep that my doctor tells me is normal for my age. My psychiatrist told me there are 2 types of people my age: those who don’t sleep well and complain about it and those who don’t sleep well and don’t complain about it.

What discoveries about aging have you found that weren’t in your owner’s manual for your life?