Age 10- the best age.. you are old enough to do fun kid stuff but you aren't a small child either.
Age 15- a very tough age, early into trying to date, low rung on the HS ladder. can be very awkward. Music is EVERYTHING to you.
Age 20- a great age. everyone much older than you is just an old fart, everyone younger is just a kid. This is the age where you actually care about things, ideas and ideals, music, art and sex LOTS of sex. Your entire life is in front of you.
Age 25- another tough age. 30 is bearing down hard, are you going to get married & have kids, are you already started on a career or are you slinging coffee at Starbucks with that fancy degree, are you still at home in mom's basement. Life seems to really pile up around this time.
Age 30- It's all real now. The age where you realize you are not going to accomplish anything great or big. You are going to work, live and die a staid normal life like everyone else.
Age 40- You are settled, you really know yourself. Life seems to settle down, kids are old enough to do their own thing now. Job, home, etc should be all taken care of by this point. You can start to travel and afford nicer things.
Age 45- see above (but 50 is looming large)
Age 50- Your own mortality is quickly becoming more apparent to you. You may have lost one or both parents and/ or dealing their issues as they enter old age. Thoughts about retirement are now a real thing, not just a theory. Your kids are now young adults that you are watching make the same mistakes you did.
Age 60- You are considering retirement and counting the days until you can stop punching that clock. You have have dealt with at least one serious medical condition. You are a grandparent and officially "old".
Age 65- If you get here without a major medical issue you are winning. You probably have lost both parents by now, your kids are well grown and started their own family. You are free to travel, but you lack the energy to do so. You may have lost a close friend due to illness.
Age 70- You have lost many friends due to illness. TV is your best friend.
Age 75+- Glad to wake up every day.