That's the age I am so that's all I can comment on presently. I think the rapid growing stage begins at 18 for pretty much everyone and slows down as you become more stable in life. For some of my friends, they're still rapidly maturing, figuring out what is meaningful to them, what they want to achieve, at 28. Some of my friends in college knew much more about what they wanted and what was valuable to them at 18. I presently have a pretty decent grasp on what I'm looking for in life and, although I expect it to change as I get older, I don't think I'm going to see the same experimentation and ballsy life choices I made at 18 and 19 and 20. I have noticed that it takes much more time and effort to change and grow now that I'm working 50 hours a week.