I have switched years ago to the shake and bake Hot hand warmers. I open and shake and put one in each coat pocket before I leave my house and my pockets are warm when I get to my stand, and if my hands get cold I stick them in my pockets. There was a post earlier bout the Johnny warmers and some were still using them. I prefer using the need that don't need fuel, no leaking no smell and they work. I carry about 6 in my backpack, normally I only use two in a days hunting, on an exceptionally cold day 4. I get them by the case. My dad used to use the charcoal sticks hand warmers and the Johnny Warmers and he was always fiddling with relighting the charcoal sticks or refiling the Johnny warmers.
When you are up to your butt in alligators, it is hard to remember your intent was to drain the swamp. Stay focused!