re·gret:–verb (used with object)
1. to feel sorrow or remorse for (an act, fault, disappointment, etc.): He no sooner spoke than heregretted it.
2. to think of with a sense of loss: to regret one's vanished youth.
3. a sense of loss, disappointment, dissatisfaction, etc.
4. a feeling of sorrow or remorse for a fault, act, loss, disappointment, etc.
I think that feeling "sorrow" or "remorse" 20 years after the fact, is a bit useless. If you learned from that action at the time and have since changed, awesome, why feel bad about teasing a kid in 5th grade when you knew it was wrong. You probably felt bad enough then, there's no reason to think back and feel guilty about it now. Of course you wish you could go back in time and apologize, or make a different decision. But you can't. None of us can.
Wishing that you had saved money, heck, I think nearly everyone looks back at their past and wishes they hadn't spent money on this or that, or that they had spent money on this or that, but it's in the past, and if you have learned from it already it doesn't help you moving forward to sit and feel bad about it. Are there things that I still feel bad about that I have done in my life? Of course! Do I have that moment when I'm feeling down and I start to watch the movie in my head of all the bad, mean, horrible things I feel I've done in my life? Of course! Don't you? For someone to say they have no regrets in life, I think they're lying, or they need to look up the definition of regret. There's not one thing in their life, that when they think about it, they get that funny, yucky feeling in their gut? I doubt it. Everyone has those things, to deny them is useless. I prefer to say "I strive not to have regrets". Of course there will always be things that I look back on and wish that I had done differently in my life, but I wouldn't be where I am now without them, and perhaps that sick funny gut feeling I get is actually helpful, perhaps it keeps me from making the same bad decision again. Maybe regret is useful. I made the decisions I did, at the time I did, based on the information I had at the time, and based on where I was developmentally at the time. Maybe it was the right choice, maybe it was the wrong choice, but all those choices have led me to where I am now, and I don't regret where I am.