The position is taken that the physical parameters of one's involvement in activity learning depend in large measure upon the objectives of the participant. General comments regarding the physical parameters of most activity classes are made. Underlying commonalities existing among these parameters are identified as: (1) freedom from disease; (2) strength; (3) power; (4) agility; (5) balance; (6) flexibility; (7) cardiovascular endurance; (8) cardiorespiratory endurance; (9) local muscular endurance; and (10) coordination. Four basic principles are posited as central to maximizing these common objectives: (1) overload (application of progressively increasing resistance); (2) isolation (overload applied to isolated muscles); (3) S.A.I.D. (specific adaptation to imposed demands); and (4) simulation (simulation of sports skills against resistance). Weight training is specifically examined for problems involved in teaching to specificity of desired effect and to individualization of meaningfulness. A brief discussion of self-concept as a psychosocial factor in activity training is also included. (MJB)