40 years old is best as you are top of maturity - all people hear what you say, you can chose well with experience i.e taking a decision on the twenties and taking a decision in you forties is a big difference. At this age you cant consider to be old or young.
Well, I was 14 when I wanted to stop growing up, but I think I would want to be an adult so that I was treated an adult, and didn't have to go to school. I think I would probably say 21. I am going to be 24 this year, so three years past it already.
19! Got THE best job, for me, which basically stayed the same until Retirement, but at different Companies.
Met my husband-to-be, & generally was having a great deal of fun! Was involved much in various Sports. Life was good!