The beatitudes are fruits, but acts which are more perfect, granting eternal happiness. The terminology is not very precise. Since the beatitudes are the more perfect fruits, all of the beatitudes can be called fruits, but not the other way around. Saint Thomas says that the beatitudes are not a special habit. The beatitudes are acts.
Happiness is attained through action.
It is important to have our moment of action in the process of beatitude. Many think heaven is just lazy. Beatitude is action, and not just action for action but action for the gift of self. Saints are people of action. The fruits are concrete acts in which the fecundity of the Holy Spirit is expressed.