god i guess i'm a big softy so. one of the main reasons why i write is because of the emotional response it gives me. i find it such a buzz. i can get an emotional response from a simple chord progression if done right. usually thats my barometer when i write, if it is not moving me some way emotionally i keep revising. it doesnt have to be crying, just any notable emotion. often when i get a brief to write its described in terms of emotions rather than musical speak so you kinda have to learn how to communicate these certain emotions in your music including sadness.