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. Saint Thomas defines the beatitudes are paradoxical acts, which are also promises. Saint Thomas quotes St. Augustine where he ties together the beatitudes, the gifts of the Holy Spirit, and the Lord's prayer. If we try to see the logic in a purely speculatively way, it will seem absurd. But if we look at them in faith, we will be open to the Holy Spirit.