What Makes You Happy?

Hunter's teacher shared with me that in preschool on Friday the students talked about what made them happy, and Hunter said, when my little brother doesn't take my toys and bother me.  When I asked Hunter about it, he said,

"No, I didn't say that makes me happy.  I said, it makes me sad when my brother Xavier takes my toys and bothers me.  It makes me happy when I go to Captain Sundae and have my favorite Sundae, strawberry."

I am glad Hunter's happy thoughts are about ice cream, but I think I am going to start reading up on sibling rivalry.  Let me know if there are any books on the subject you recommend.