Yoga tonight

I am going to go to the Hot Vinyasa yoga tonight. It is different then the P90x yoga but still very tough. I need to start drinking water now so as to not faint or cramp up during the session. I do not do well with heat. It should be a good workout and I will give you all a catchup on it after or the next day. Also my heart rate monitor is working but....my watch is out of batteries and of course it is not user replaceable. Almost genius if you ask me. Nevertheless, I will work that out at some point.