In my opinion the best we can do is living in the moment and make sure not to have regrets. If people have regrets it means that they don't really like the person they actually are and think they should have done things an other way. We must be proud of what we did, and to do so, we need to dare acting. Want to talk to this person, to travel, to change jobs, to say “no”... just do it. Nothing worse than staying stuck in a life which doesn't make you happy could happen. I've started to be truely happy since I behaved in agreement with who I really am and in the same way whether I am with my family, my friends or complete strangers.