The warmer they are and more humid their environment is, the more active they will be.

One of the biggest problems customers had when I worked at PetCo was they did NOT mist their hermit crabs multiple times daily and keep the cage humid and they ended up dying. So if you can make sure to provide the hermit crabs with the most ideal envirnoment possible, keep them nice and WARM and keep it HUMID, they are actually really fun to watch