Glasses always fog up when i ride?

i wear glass and when i ride my glasses tend to fog up a lot and its dangerous so i have to travel with my visor up and the wind makes my eyes watery and the wind noise is not good for my hearing as well. so i was wondering if there is something i can put on my glass so they dont fog up. i tired the "Rainx Interior Glass Anti-fog" on them with no success. maybe i did it wrong. but wondering what you guys out there with glasses do?