Many people are so caught up in their past. Either because they think it was better than their present or they use it as a crutch for how they are now.
The majority of people I've seen use the past as an excuse to be difficult, bitter, depressed, unmotivated, etc... Then there are those who always want to relive the past because, in their minds, they have made it out to be some kind of paradise. They think their present is so bad, they have purposely forgotten the rough times in their past.
I guess what I'm trying to say is, most people are so busy looking behind them, they don't see what's in front of them.
None of us have really had it easy. Every person can look back and at some point in their lives, and pick out more than one traumatic moment. Abuse, neglect, a loved one dying, being picked on... Some big, some small. Fact of the matter is, we all have those things in our past.
Here's the trick. Learn from your past, but don't dwell on it. Recognize it, own it, accept it, but don't keep reliving it. It can't be changed. It can't be brought back.
The first step in accepting your past is accepting yourself. Accept yourself for who you are. Once you've accepted yourself, you can love yourself, and once those things happen you'll realize that everything that happened in your past has made you who you are. If you accept and love yourself, you can't possibly regret anything in your past. You can't find that acceptance and love outside yourself. It can only come from within.
And for those who think their past is better than their present is selling their lives short. These people need to get back in touch with themselves and their loved ones.
This is all easier said than done.... but believe me, it's not impossible.