I share the sentiment. I'm not unhappy by any means, but I simply find no joy in life, or things which happen to me anymore. We had friends over last night who came with their 5yo son and I was watching jealously at how he found everything endlessly fascinating. I don't want to have a son; I want to be 5 years old again. Or at least, to find fun in the world.
I was thinking earlier that I haven't been "happy" in about 8 years. I had to think really, really hard to when the last happy period was.
That fucking sucks.