My life is meant to be lived. I'm alive for a very short time. I refuse to spend it looking over my shoulder; second guessing everything. If I do something stupid or harmful I made amends (or try too). I redeem myself for my own peace of mind.
Look it boils down to this: what does every faith on the planet teach? I'm not typing about the differences or whose god is stronger or better, I'm talking mythos - they all teach that it's all about how we treat each other. That's what it all boils down too.
I'm mortal. Of course I have regrets. I don't live for the moment (like dogs - or do they... I have doubts about that) I don't believe regrets are "negative". They're a part of life. We've all had missed opportunities. We've all treated someone poorly. It's life.
If I step out of the house right now and get hit by a bus, it's the living; they'll have to sort my life out. But I hope I have the luxury of facing death with time to reflect on my own life and realize, hopefully, that I lived; had a great time; and left my mark.
It's a good question. Too much paper has been spent on rehearsing the same story of "Do things now because when you are old you'll be old and it wont be as fun and you'll regret it because you'll be old". That is, in some parts, absolutely true but I feel it would be better distilled down to the basic motto of 'Do more'.
Even with that you'll still have regrets. My mom had a serious stroke early into retirement and all of her cross-country planning went away with it. Even though she's done this type of trip before she still regrets not being able to do it again. Regret is part of life, we will always feel like there was one last thing to do, we don't die with all of our dishes washed.
Acted regret serves to say, "Why did I do that? I should have known better. I'll remember not to do this again."
Minimizing missed regret is just quieting your ego and moving forward so opportunities don't pass you by. Minimizing acted regret requires seeing all possible futures and avoiding ones with high probabilities of failure (but that's quite boring).
"I get up every morning determined to both change the world and have one hell of a good time. Sometimes this makes planning my day difficult."
Then there are those activities that we didn't do and didn't even consider. Not spending time with family before it's too late, not finishing a big project due to laziness, etc. These I'm more prone to regret.
And it is often only in hindsight that I can tell the difference. Often, because I reflected on it, I learned something from my mistakes, but regret came with that learning. I suspect that for most people the only way to avoid regret is to avoid reflecting on life.
And if you-then hadn't made those decisions, that would have helped to make you-now a different you.
Unless you value being "who you are" instead of "who you might have been" more than you care about the suffering you caused, it's not clear to me why you shouldn't regret those decisions. (Note, I'm not saying you shouldn't prioritise your values like that, especially if it was mostly you who was suffering.)
This is mostly nitpicking. I agree that there's a difference between "I regret doing that" and "I regret not doing that".