The eightfold path to the cessation of suffering teaches:
6. Right Effort:
Foster good and prevent evil;
Work on yourself—be engaged in appropriate self-improvement. The essence of right effort is that everything must be done with a sense of proper balance that fits the situation. Effort should be balanced between trying too hard and not trying hard enough. For example, strike the balance between excessive fasting and over-indulgence in food. Trying hard to progress too rapidly gets poor results, as does not trying hard enough.
taken from: ‘The Essence of Buddha’s Teachings’