What can I use on my eyeglasses to keep them from fogging?

[Anacortes]

When I wearing my riding goggles it keeps fogging up, I even cannot see the road clearly, it troubles me a lot. What can I do to keep them from fogging? Can I use spray on it?

[Anadarko]

It is quite annoying .The problem is often caused by a warm and humid climate.When moving from one temperature extreme to another (for example, from an air-conditioned building into the hot outdoors), allow your glasses to acclimate before wearing them. Keep the glasses in a sunny window while indoors, or wear them on top of your head for several minutes before stepping outside. Preventing the lenses from experiencing any temperature extremes will make fogging less noticeable.