Recently, as a new father, I would wake up in the middle of the night to care for my son. I would drag myself out of bed feeling horrible, achy, brain half-functioning, and irritable. My back felt like it was going to tear open from lifting him from the wrong angle for the hundredth time that day..
..But then he would smile at me. A look of absolute joy at being there, just hanging out. He would make a little excited giggle-gurgle (which is the happiest sound a person can make) and I would start to cry out of exhausted happiness.
It's a moment I love so much I wanted to share.