I don't really "believe" in regret. At each and every point in my life, I was working with the information I had at my disposal, each information having its own "weight" in my mind. Every mistake I've made has brought some information in my mind that wouldn't have been brought otherwise. Fantasies of "changing the past" are seductive, but ultimately pointless. The only way I could justify having regrets, is reminding…
As are ones about making an unlikely future come to be. When I find myself sidetracked by those thoughts I now say to myself "Get out of fantasy land where unicorns fart rainbows" and it seems to stop.