I have discovered the secret of Time Travel. So this is it. Can I trust you with this secret? This is what you do:
1. Find someone you really like. Go on. There's someone.
2. Sit beside them in class. You can do it. It's a free country.
3. Say; Hey! you have awesome hair (or some equivalent).
4. And when they look at you like ... eh... thanks I guess, now don't talk to me, then,
BOOM! You are thirteen.
Feel free to test this theory. You are welcome.