[W]e find that different kinds of past pleasures and pains do not equally admit of being revived in imagination. Thus, generally speaking, our more emotional and more representative pains are more easily revived than the more sensational and presentative: for example, it is at this moment much more easy for me to imagine the discomfort of expectancy which preceded a past sea-sickness than the pain of the actual nausea: although I infer—from the recollection of judgments passed at the time—that the former pain was trifling compared with the latter. To this cause it seems due that past hardships, toils, and anxieties often appear pleasurable when we look back upon them, after some interval; for the excitement, the heightened sense of life that accompanied the painful struggle, would have been pleasurable if taken by itself; and it is this that we recall rather than the pain.
(Henry Sidgwick, The Methods of Ethics, 7th ed. [Indianapolis: Hackett Publishing Company, 1981], bk. II, chap. III, sec. 5, p. 144 [first published in 1907; 1st ed. published in 1874])
Note from KBJ: This passage explains why people run more than one marathon. I've run 11. I've done many difficult (and painful) things in my life, but nothing as difficult or painful as these marathons. As I like to put it, I hate running, but I love having run.
Keith Burgess-Jackson, J.D., Ph.D. 