“To love our enemy is impossible. The moment we understand our enemy, we feel compassion towards him/her, and he/she is no longer our enemy.” ~ Thich Nhat Hanh
The first of the brahma-vihara is called metta.
Metta is loving kindness toward all beings without discrimination and without attachment. By practicing metta one can overcome hatred and anger. To cultivate metta, bring to mind a time when you acted in a way that was kind, loving or generous. It can be something very simple, like cooking a meal for someone or opening a door for someone. If you can’t think of anything, you can always bring to mind the desire to be happy, as that is an inherently good state. Meditate by repeating these phrases:
May I be happy.
May I be peaceful.
May I be safe from harm.
May I enjoy happiness and the root of happiness.
May I experience ease and well-being in body, mind, and spirit.
You might practice metta for yourself for a short time or a long time, it totally depends on you. Once you have cultivated loving kindness for yourself, though, you are ready to cultivate it for others. Start with those closest to you and then expand the circle out to people for whom you have neutral emotions. Next you will practice metta toward someone for whom you have more intense negative emotion; perhaps someone you feel has wronged you in some way. Finally you will practice metta toward all beings.