Regret is cumulative. It is built up from bad experiences, so that your ego can process and steer towards better experiences or avoid the bad ones. Sometimes however, bad experience can also cause an individual to avoid good experiences.
Psychotherapy can help, so can the use of Magick to “sacrifice your regrets in the burning fire of the altar of the Gods of ancient”, it can be a ritual or it can be performed as a mystical operation, or even IOB (Modern Magick, D.M. Kraig).
The point is, when you have magickally or scientifically removed Regret in its many incarnations (remorse, doubt, fear, anger, etc), you must have learned, or you end up restarting the process of accumulating regrets.
Don’t let regret keep you from having new experiences.
Do let regret give you an indicator of what you like and what you don’t like.
What you like and what you don’t like are guidance pointing at your True Will.
Just as the monk pointing at the moon is not the moon, those experiences are not, your True Will.