How do I keep my safety goggles from fogging up?

When I am trying to work with the string trimmer and get hot and sweaty my safety goggles fog up. I don't wear my safety goggles anymore while trimming because of that.

Well, first, if they are fogging up that usually means they don't fit well and you should probably look to getting a pair that fits properly. As for the fogging, that can often be fixed by spitting on the inside and rubbing it around to coat (sounds stupid but it works), you can use vinegar to do the same thing, or you can use commercial products like Rain X.