What are your life’s could have, should have, and would have things or occurrences?

When you look back over your life what are the things you felt you could have, things you should have done, and things you would have done, but somehow never did, or failed to avoid? Such as, you could have went back to school and got your BA but went to travel Europe instead, you would have quit smoking but somehow never got to it, you should have never bought a house with that person but somehow did, etc.