We cannot learn real patience and tolerance from a guru or a friend. They can be practiced only when we come in contact with someone who creates unpleasant experiences. According to Shantideva, enemies are really good for us as we can learn a lot from them and build our inner strength.
Live in a Better Way: Reflections on Truth, Love, and Happiness (ed. Penguin, 2002) - ISBN: 9781440650284