I've gone through many changes in my life and now that i'm in my 30's (ugh that's weird to think) I can look back and am happy i went through the things that i did. i wouldn't change a thing.
To me my actual turning point was when i was 25, you feel different think different and you're pretty set as to who you are going to be as a person, but you just become more confident as the days pass.
I agree with Juicy, age ain't nuthin but a number. i still get carded, people freak when i tell them my age and I still feel as young as i did as i was 21.