For a person who cherishes compassion and love, the practice of tolerance is essential, and for that, and enemy is indispinsable. So we should be grateful to our enemies, for it is they who can best help us to develop a tranquil mind.
The past is past, and the future is yet to come. That means the future is in your hands - the future entirely depends on the present. That realization gives you a great responsibility.
It is felt that a disciplined mind leads to happiness and an undisciplined mind leads to suffering, and in fact it is said that bringing about discipline within one's mind is the essence of the Buddha's teaching.