Personally, I don’t consider the act of rewarding myself. However, the positive effect that a gratification can have on your motivation to study is stupendous. If you feel the urge to become motivated to study, set yourself a goal (as discussed in I. The motivational power of having a goal) and determine an appropriate reward once the objective is accomplished. It’s really that simple, but so effective. By rewarding yourself, whenever a goal is achieved, your brain elicits positive emotions, leading to the realization that an effort results in a positive reward. Hence you increase your motivation to study which allows you to maintain your motivation on a high level until the objective is accomplished. Also, your willingness to make an expenditure (e.g. studying) in order to accomplish the objective (e.g. an excellent grade) will raise, when having a reward in mind that you have desired for a long time.