If you become uncomfortable you will become distracted and have to move. If you move your body you have to start all over again. Preferably have your palms touching another part of your body, like your abdomen. This allows for a good energy connection which is very important in the use of this particular technique. Don't forget a blanket or warm clothes.
Socks are especially helpful.
Close your eyes. Completely relax your mouth and your eyes. This is actually a technique that I use in training singers. Relaxation begins with the eyes and the mouth. If you completely relax those two features in your face the rest of your body will follow suit.