Answer:
Positive incentive
Step-by-step explanation:
Positive means a desirable or a constructive quality or attribute.
While a positive-incentive value is the anticipated pleasure that is involved in the performance of a particular behavior or action, for example, eating a particular food or doing a particular thing to get sometime constructive (positive) out of it.
Hassan said he would stop weightlifting if he doesn't see changes on his body.
Hence he is looking for a Positive Incentive.