I try to regret as little as possible.
I believe regret leads to only dark and hurtful thoughts. I suppose that if you look at any disision (it’s disision that make regrets) it’s to not make it a flippant one. Take time and make sure you have covered all aspects.
Looked at all the relevant paths and discarding the weak ones. What you are left with is the few true remaining paths. This for me limits the potential for regret.
It’s not foolproof, I have some regret to disision I have made but I am happy that at the time they seemed right. Hindsight is a wonderful tool only for a time traveler. Us simple folk will just have to make the best we can with what we have.