Instead of carrying around those hand warmer packages that look like giant moist towelettes that last for an hour or two, you might want to consider a Zippo hand warmer. Shaped similar to a giant Zipp.
Zippo Hand Warmers -- Do not let cold weather stop you from doing what you want. This zippo hand warmers can keep your hands warm. It does not produce flame and has easy fill technology. It can provide 12 hours of continuous warmth.