tears for fun?

why do we do things that we know will make us cry? is it a girl thing or an everyone thing? i ask this because i'm reading a book right now that was recommended to me with "you'll like it. it's really good, you'll cry for sure." the same has been said during movie recommendations. why is it that if a movie/book will make you cry, it's considered a good thing? i guess it's because its a work of fiction that creates real emotions in you and we all like to live vicariously through characters in books and films. we like to travel away from our lives from time to time, and experience someone else's. but still, why do we choose ones that will make us cry?
when you're upset you might go and listen to sad music or watch a sad movie etc that will make you cry it out rather than make you feel happier.

i'm not meaning to criticize any of this. i'm one of the worst offenders for this. i really do love when books and movies make me cry. i like feeling intense emotions for these make believe characters. i'm just wondering aloud as to why.

what book is making me cry? *sigh* i hate to admit it, but it's dear john. yes, a nicholas sparks novel. all of his stories are the same (this conclusion is based on the notebook (movie), dear john (book) and the last song (which i haven't seen, but know enough about). a boy and girl meet. they're from different sides of the track (rich/poor, trouble maker/saint, etc). they're together for a summer and somehow fall head over heals in love. then they are forced apart and they try to cope without each other, or how to cope with the struggles in their ever changing relationship.
all the stories may be the same, but they do work. everyone can relate to the story in one way or another. i bawled in the notebook. i've already bawled several times in dear john (and i'm only half way through!)