In my opinion study routine id extremely important; routine leads to a habitual response to study, which is essentially the most vital aspect needed for one to study consistently and effectively. (We are creatures of impression, habit, and reaction. There is no magical trick or force which compels you to study or be intelligent.) You cannot force motivation on yourself, working on motivation alone is insufficient and never leads to genuine progress.
And for the matter of intelligence, one can have the inherent aptitude for learning, yes. But intelligence itself is relative to the viewer and therefore cannot be taken as an objective concept or icon. Humans are so very malleable to their environment and so much of that influence goes unnoticed. Say; sociable traits one has picked up, impressionable stereotypes they have taken as habit,(ie. Masculine = Strong or Skinny = Weak, these can be seen as impressionable icons in which we derive some form of meaning from some symbol. And it goes far beyond these not-so-subtle examples.) Or moral values they have taken as a societal basis.
That is also how religion is so rampant, individuals are born and cultivated in environments which promote certain things for them. And given that is their only basis they grow in that direction.