Laughing Baby

I remember learning in Developmental Psych that a baby's first real laugh usually comes out a moment of fear.  She thinks a bad thing is about to happen, then it doesn't.
You can test this out with a young baby (when she is in a receptive mood :) by holding her in in your arms so she is facing you, then quickly lowering your arms by six inches or so, coming to a sudden stop. Make a big surprised face, then smile. Do it again, if she didn't mind too much. It's kind of like telling her a joke. Some babies find this kind of thing hysterically funny.  Others, just hysterical.

Or you could just try ripping some paper.

My daughter's first big laughing session happened when a four year old boy was visiting. We would sometimes put her soother in her mouth upside down because it amused us to watch her rotate it back to it's proper position without moving a muscle in her face. Well, he had never seen anything so funny, and his laugh was so contagious that soon she caught on, too. We kept up the cycle of upside down soother, popping right-side up, he laughs, she laughs until her soother falls out, put it back in upside-down until we were all exhausted.

Baby laughs are good for whatever is bothering you. If you haven't seen these, they will lift your heart.