You can use small 12V notebook fan with 9V charging cell to prevent fogging. It is quite cheap and it will help prefent fogging even in heavy conditions, reliably... but the sound is little annoying after while - the fan can you not heard even on ideal conditions from 6 feet distance, but when he is very close to your ears... it is not much good solution for long woodsball play, but if you are speedball player...
If you do not wish use thermal lences, anti-fog spray, or fan, simply choose good mask with good sealing and ventilation (or improve your curent sealing and ventilation holes) and wipe off the sweat and impurities from lenses, seals and even from your face regulalry in between of games (!). When you will do that, then you will have minimally half hour without fogging, everytime.
...for cleaning of the lenses is very good toilet-paper and the main asset of the anti-fog sprays is often that they help you clean the lenses.
Likewise is good use wind as natural fan in the game, move continually and avoid to stay in damp lowland places or crawl, especially in wet grass.