In some aspects, a system is provided that includes (1) a plurality of mobile devices; and (2) an application on each mobile device, the application adapted to (a) allow exercisers to form an exercise group; (b) track position or change in position of each exerciser in the exerciser group; and (c) display an avatar having a position that is controlled by a position or change in position of one or more member of the exercise group. Numerous other aspects are provided.