My personal philosophy has long been to not regret. My basis for this is fairly simple: given the assumption that the total outcome of your life’s decisions has led you to where you are, if you are happy, then you have nothing to regret. After all, even the bad or “wrong” decisions you made were part of what got you to a happy place, so there is no reason to regret them even if you recognize that they were incorrect.
I certainly don’t mean for this to be the sort of thing that everyone takes to heart; there are dozens of reasons for any given person to disagree with me, even if they are by my standard perfectly happy. However, for me, it has worked. I have made plenty of incorrect decisions in my life, but the place where I resided was, after a fair number of bumpy spots, generally happy.