Changes, you notice them most in the young and in the old.
The restaurant is great for this. People you recognize as old one season are suddenly much, much older the next. And children quickly become young adults, young ladies who'd come in for a fries to-go and never tip suddenly begin eating in and tipping 20%. The changes are dramatic.
In people our own age we seldom notice change. They age pretty much like us, and unless we haven't seen them for a few years will probably recognize them pretty much as they were. But change accelerates when you get older, one slip or fall and decrepitude pounces.