This is how I always think about, fragment life into stages, so that I can't get lost in time. I am 41, and I made a statement to my self, that when I enter 40s and still don't have a running business, I would better not try again. But after spending my 30s studying and collecting data for my startup, it was hard to drop all that effort, so I gave it one more push, until I launched my startup on my 41th birthday. Hopefully i will begin to collect the fruits I have planted.