Scuba divers have the same problem with fogging masks. here are a few tricks to try. clean new glasses/goggles with non abrasive toothpaste, this takes off any production coatings. Older goggles wash with dish soap. to keep them fogless; try rain-x and rub it off really well. Another product that works like cat crap (great name) is Sea-Drops. But most important if you're out on the trail and fogging, spit onto the lens and wipe it off just enough so you can see. I also have used chapstick to put as thin a layer on the lens as possible...sounds like I need a new dive mask.