"You only regret the things you don't do." This quote is the foundation of my philosophy, essentially saying you need to go live your life. However, my 17 years of life--that I pretend have made me wise enough to preach on the internet--have given me life lessons to use to expand on this quote and form my own original philosophy. Simply put: don't regret at all.
Granted, this is easier said than done. Although regret is a natural reaction, it should be handled like a china doll: carefully, although it serves no real purpose. Regret is positive as it shows you possess empathy often times, but there really is zero purpose in regret. See, there is only one person that is guaranteed to be with you throughout the entire course of your life: yourself. So you darn (we're a PG blog here) well better like you. But you haven't always been the same, you've had different versions of yourself. At one point, your past self might've done something that your current self regrets. However, you have to respect that former version of yourself, he/she thought it (whatever it was) was a good idea at the time and carried through with it. Sure, there could be legitimate reasons to regret those actions or words, but by regretting this, you're betraying that former version of yourself. With enough regret in your life, you'll hate just about every form of you that you've ever been; until eventually, you despise your current self for being related to those people. And now you hate yourself, and you're stuck with him/her for the rest of your life. Nice going. Yes, I'm aware this could be viewed as the slippery-slope overstatement of life. I just believe that you should instead understand that you aren't necessarily so closely related to those former versions of yourself; consider those versions only a distant cousin or hated step-sibling and move on from your past. Give yourself some credit for the growth you've endured. You're different now. Trust that.
So, don't regret. Everything is a learning experience if you try hard enough. But also, don't ever be mean to your mom or cut your own bangs in your bathroom, you'll always regret that.