Lemmings enjoy any kind of running or climbing; however, as their habitat is essentially flat and rather featureless terrain, they have a poor sense of height and danger, so their enclosures should not be high enough to allow them to fall more than 10–15 cm and should, of course, be lined with wood chips and hay. An exercise wheel is the best way to keep the animals busy and trim, and if the wheels afford enough space, they will often race in it together. (However, fights can often develop around wheels - with males, particularly, it is helpful to have several wheels, perhaps even one for each lemming.)