When I look back on my life I realized that I have difficulty in letting things go. Instead, I just repressed everything all together and obviously this isn't healthy.
All that you need to do - is to make best decisions in real time situations. When you make RIGHT things RIGHT NOW - you can't say in future that you did wrong thing. It's really easy to say anything about past being in future and being able to see all consequences.
Never regret.
Think.
Earn experience.
Upgrade yourself.