Negative reinforcement can be very effective at curtailing any bad habits you might have. Put a rubber band on your wrist. Then, any time you find yourself needlessly worrying, just pull on the rubber band, and let it snap hard enough to sting. If, shortly thereafter, you start worrying again, pull that rubber band a little further so it stings even more. Repeat as needed.

A less painful technique for addressing this is to click on the following link, have a laugh, and then vow to stop being "that guy"...

https://www.youtube.com/watch?v=Rdk-rHAndNc

Meditation has helped me a lot. It helps the "you" that wants to stop worrying to be present. You learn how to be aware that you're worrying while you're worrying. Then you can stop it by gently placing your attention on something positive or constructive. The more you do this, the easier it becomes.

One really good technique I've learned is to write your worries down on a piece of paper. Once you do that, you realize how ridiculous most of it is.