A friend just gave me an old pair of skiing goggles for my cold weather commutes. The only problem is that I wear glasses, and they fog up big time after about 5 minutes of riding. Any suggestions? Are there any products that actually work to keep lenses clear, or maybe I need to upgrade to a better pair of goggles (ones with fans, for example). I'd really like to do something about this, I'm so sick of having frozen tears stuck to my face! Thanks!