To think good thoughts requires effort. This is one of the things that discipline – training – is about.
Discipline is the suppression of base desires, and is usually understood to be synonymous with restraint and control. Self-discipline is to some extent a substitute for motivation. Discipline is when one uses reason to determine the best course of action regardless of one's desires, which may be the opposite of excited. Virtuous behavior can be described as when one's values are aligned with one's aims: to do what one knows is best and to do it gladly.