1. A device for occupying a human subject with physical and mental activities, comprising: (a) a human mountable and movable object having a total volume in a range of between about 0.5 cubic meters and about 5 cubic meters and being sufficiently strong to bear weight of the human subject when the human subject is mounted and moving thereupon; (b) an object motion control assembly operatively connected to said object, for controlling motion of said object when the human subject is mounted and moving upon said object; and (c) a base assembly operatively connected to said object motion control assembly, for anchoring said object motion control assembly when the human subject is mounted upon said object and moving upon said object within a field of space determined by characteristics, configuration, and dimensions, of said object, said object motion control assembly, said base assembly, and according to behavior of the human subject.