Desire destroys devotion, anger destroys wisdom, greed destroys work - hence these bad qualities must be sacrificed. With good and sweet words, keeping desires under check and control (for ultimate removal), one should start on the path of sacrifice.
Service expresses the divinity hidden in man. It broadens one's heart, it destroys narrow-mindedness, and it gives delight. The evil qualities and tendencies in us can be driven away through service.