There are two things that can happen when you choose a road: Either you'll regret, or you wont. And almost always, we regret. We wished to have done this instead of that. You can't stop regretting. I wish I had done this instead of that.
But what's funny is that you'd regret if you'd done that instead of this. I like to see the act of regretting as a part of muscle, just like idea muscle. If we keep exercising it, it will grow stronger and stronger.
For example, a person who regrets a lot will regret on everything regardless of the decision s/he makes. The person won't be satisfied with anything. Everything just leads to regret.
If you buy a blue car, you wish to have bought a white car. If you buy a white car, you wish to have bought a blue car. Regret just lives with you.
I figured this happen to me. Whatever I do eventually leads to regret. If I buy a small mobile phone, I wish I'd bought a bigger one. And if I buy a bigger mobile phone, I wish I'd bought a smaller one. Nothing satisfies me.
To stop regretting, I started thinking of not exercising the regret muscle. For that, I not only try and not regret my decision, but also make regretful decision and try to not regret it.
If I know I'll regret buying white shirt, I'll buy white shirt and try to not regret. It's difficult, but with time, I guess I'll get better at it.
By doing things that will make me regret, I'm learning to not regret.