eustress noun:
a good kind of stress. An example of eustress is the anxiety one might feel while trying to set a new best time for a 5K run. Another is the elevated level of concern one might feel studying for – and then writing – an important exam.

Typically, eustress surrounds a situation the person voluntarily embarks. Furthermore, it likely has a decisive ending. The person perceives a benefit, so is willing to risk effort and uncertainty to gain it. The person believes that, by applying their own wherewithal, they are able to accomplish the objective.