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.
Dalai LamaIf a problem is fixable, if a situation is such that you can do something about it, then there is no need to worry. If it's not fixable, then there is no help in worrying. There is no benefit in worrying whatsoever.
Dalai LamaNot only can I not recall my experiences in my previous lives, sometimes I can't even remember what I did yesterday.
Dalai Lama