Another helping topic for lens fog is to use roll on anti perspirant, I play paintball a lot and have never had good luck with the anti fog spray so I switched to rubbing a little anti perspirant unscented around my eyes and I don't seem to have any issues seeing whatever the weather. Definitely try this a couple times before going on a troop though as too much can run. Go with the unscented so its not overpowering in your bucket and it also will help prevent runs and burning a little bit better. Just a little experience from paintballing and swimming lens' fogging on me for years.
