Its probably your face mask. I have had fogging problems since I can remember with at least 3 different pairs of goggles. I've tried the Serius half mask, a north face neck gaiter, and a bandana and they all fogged my goggles. I learned they were all sending my breath up into the goggles and making them to fog. Tried cat crap, fog cloths and spray too.
Last season I picked up one of those under armour masks and the problem dissappeared. Also, as someone else mentioned, DO NOT rub the inside of your lens.