Used to describe how you feel inside when you find yourself in a pleasing set of circumstances, or at least in comparison to a worse outcome that also might have occurred. It does not suggest glee at another's misfortunes but rather highlights one's own fortunate situation.
eg. 1: The forecast predicted rain for our camping trip, but the weather turned out to be so gorgeous we were laughing.
eg. 2: While waiting at emergency, I was upset over my ankle injury. But then when I saw the paramedics bring in a 7-year-old girl covered all over with first-degree burns, I realized I should be laughing.