Hey, thanks everyone, your answers are very helpful, however, I still am not sure if you guys are actually having, and getting past your convulsions while under water??? Or is it just a static ( dry ) thing? I just find it difficult to feel like im running out of air at my usual 2 minute mark, and then just keep holding forcefully my breath through convulsions and mental anguish while at 50ft. So is this what you guys do???