Expectancy-Value

Why  do  some  individuals  participate  intensely  in sport activities over many years while others never get  actively  involved  in  sport  or  exercise?  What influences  initial  participation  in  sport  or  exercise?  What  influences  continued  participation? What  influences  the  intensity  of  participation? How do we explain drop-out from sport and exercise  engagement?  How  do  we  explain  both