Ok, so worries do not make things happen. SO, maybe they serve this purpose: Maybe worries work by having us think of every bad thing that might happen. If we can do that, then we can prepare for every bad thing that might happen. And, if we are prepared for every bad thing that might happen, then we will not need to worry about it anymore since we are ready for it.
This sounds like it takes a lot of effort, but it is what a lot of people do, and it is another huge waste of time. For example, I could offer you a free trip to Hawaii and you may say that you appreciate it very much. Or, you may say that you are not going to go because: There could be a fire in the hotel, a shark might eat you, you might get lost, there could be a slippery rock by a waterfall and you might slip on it and break your neck, you could drown, and then there is all that lava!!! Well, it seems that there is no way we are going to Hawaii - it is just far too dangerous.
If this is the way you look at things, then nothing will be fun, or exciting, or rewarding. Everything will just be a potential disaster diverted. When you look at everything like this, then there is very little to look forward to. So, you then start to worry about all of your worries, and an unending cycle is begun.