"Don't worry, be happy", so goes a popular song from way way back. Indeed, why worry? I've read somewhere that worry is like a rocking chairyou never really get anything from it, yet you still keep on doing it. Usually, worrying stems from living in the past, preventing future regrets or mistakes to happen again. Or what the future may bring.
For you to stop worrying, you need to:
1) Stop living in the past. We all made mistakes, misdemeanors, regrets, follies of our youth, etc. It's already done in the past and time to move on. What you can do now is to learn the experience coz we can't do anything about it anymore. Regretting about the past is simply useless.
2) Stop worrying too much about what the future may bring. Learning how to stop worrying is realizing that you can't predict what will happen tomorrow or the day after tomorrow. Still, it's important to note that in almost all areas of your life, remind yourself that you are still in control of your own life. So stop blaming the outside world for your own woelike other people, the traffic, the government, the weather, etc. It's true that there are stuff which are beyond our control, but believe that in your hands lie the power to choose how to act or think.
3) In order to be happier and less worrisome, just choose to be happy! Too often we think that we need more stuff so to make us happier. But actually, it's so much easier to do it the other way around. If we choose to be happy, then things will just fall into place. Make a list of the things you're grateful for or the great things that happened to you. Yes, it can be all the small things, like the food that you enjoyed, bonding with friends, free from pains, being healthy, sincere compliment you received, and add up all those stuff you're grateful for.