What do you know now that you wish you'd have known when you were younger?

That you actually have to eat healthy, exercise, and work hard to be good at sports. My natural abilities only took me so far, then my poor work ethic and poor diet allowed everyone else to pass me up. Granted, I probably wouldn’t be a professional athlete either way, but I’d probably have more stories of my glory years that I’d be able to bore people to death with if I had just worked a little harder.

Be yourself no matter what.

That no matter what you do or how hard you study the subject, the ways of the female mind will always remain an enigma ;-)

Credit cards are not as good as they appear.

All of my sports knowledge… final scores, stats, etc.
Just like in Back to the Future but I wouldn’t be like Biff

and if that wasn’t possible I wouldn’t have quit piano lessons when I was 12… I started when I was 8 and could probably be a badass pianist (always sounds like penis) and be rocking it out with a sweet rock n’ roll band.

Be yourself, no matter what ANYONE tells you, and this includes parental figures, especially as you go through adolescence to adulthood.

I spent too many years trying to please certain people and hid aspects of myself that made them uncomfortable. It was an utter waste of time and resources. I’m still crawling out of the mess I created from doing such damage to myself.

Like Tennesseejack, I would like to know what stocks take a dive and when. I wouldn’t be able to remember the sports scores but I would remember when to invest.

Heh, some great answers here, keep ‘em coming :)

I’m talking about life lessons, of course, things you learned the hard way, not sports scores :P

I wouldn’t take lessons like that away from young Bodyhead. I’m a better person because of all the crappy events I experienced.

Put that cigarette down. Having my first one was the worst thing I have ever done. And I took a shit on some guys lawn while my friend Brian siphoned the gas out of his car.

I miss high school

To stick with it once you find something that makes you happy. Letting go of it is one of the stupidest things you could ever do. Trust yourself and your instincts – ultimately, they will not lead you wrong.

Accept the fact that people with experience usually do have something to offer and that experience usually does come with age. Their take on a given situation may not be the same as mine will prove to be, but as least they have a take, they are not just basing their opinions on speculation or the arrogance of the uninformed.

The most important things in life are our relationships with others. Put the diligence and effort into those that you normally put into your career.

That I was not fat and should never have thought I was fat, ‘cause now I am kind of fat and I know it.
I should have been happier with myself.
Ah, youth is indeed wasted on the young.

Guys that are dangerous and exciting are fun but bad for you in the long run.

It is better to be alone and relatively happy than coupled up unhappily.

You don’t need as much stuff as you buy.

And, it wouldn’t hurt to exercise a little more.

Just to relax. Things don’t get any better if you worry about them.
And to take care of my self before I take care of all others. My own health first, THEN I can do my best for others!
Ooh, and that my final exam at nursing-school was about paranoid schizofrenia, that Andreas (5 grade crush) had a crush on me, and that love ALWAYS shows up when you least expect it.

That other people are not nearly as concerned about how you look as you think they are.
I could have called the police myself.
Never start smoking.
Sex without birth control is stupid.
Things always get better.

That the genes for bipolar disorder run rampant in my extended family. No one ever tells the truth.

I was just thinking about this questions while I was solving a server lock up problem at my work. I would go back in time and tell young bodyhead that it’s far more important to look and act like you know what you are doing then to actually know what you are doing.

Dress trustworthy and speak with confidence and people will believe anything you say.

(that’s a little more in the true spirit of the question)