[jpasden]

I think there are only two ways to deal with regret: (1) accept that you can't change the past, and (2) make sure that you learned something from your mistake(s).

Not learning from your mistakes at all and continuing to suffer from them is enough to depress anyone. So if you haven't yet learned what to take away from your experience that will help you in the future, concentrate on that.

Also, early 30's is NOT too late to start over, in almost any field. You just have to find something that you're passionate about, and yes, you do have a lot of catching up to do. There are a number of success stories out there that start that late in life. Read about them. In some cases, experience gained from early failures even make for bigger successes down the road.