halfhearted — showing little enthusiasm, effort, or interest; lacking commitment or determination

a teenage basketball player slowly dribbles the ball with slouched shoulders and a bored expression. He barely lifts his feet while moving and holds the ball loosely in one hand. The coach points energetically at the basket, trying to motivate the player to shoot. The player responds with a weak, underhanded toss that falls far short of the hoop. Other teammates on the bench shake their heads in frustration at his poor effort. The coach throws his hands up in exasperation at the lazy attempt. someone performing with little enthusiasm, effort, or commitment