Intense emotional states are remembered more readily than mundane activities. (Giuffre, Kenneth, MD. The Care and Feeding of Your Brain. p 48. NJ: Career Press, 1999.)
Strong emotion fixes specific moments in the memory; you are more likely to recall those times of strong emotion. Emotions can also amplify an experience. (Ornstein, Robert. Multimind. p 106-109. NY:Doubleday, 1986.)
Refer to Memory and the Brain for additional information.