There was a young man who tragically lost his arm in accident. Because he could no longer do things he enjoyed that required the use of both his hands, such as playing the guitar, he fell into a deep depression. One day he finally decided to just end it all. So he went up on the roof of a tall building, intending to jump to his death. But he was surprised to see that another man was already up there. Even more surprising, this guy had no arms at all, but was dancing around and whistling. The guy with one arm thought, "Gee, here I am with one arm about to commit suicide, but this guy has no arms and all and yet he's dancing and whistling like he's the happiest man on Earth. And there's still a lot of things I can do with just one arm." This brought the one-armed man out of his depression and he decided his life was still worth living, so he walked up to the dancing armless man and says, "Hey, I just want to thank you, you just literally saved my life!", and then he tells the armless guy the whole story. Afterwards the armless man said nothing, but continued to dance around and whistle. The one-armed man asked, "Hey, why exactly are you dancing around, anyway?"
The armless guy tells him, "I'm not dancing, I've got an itchy butt and I can't scratch it!"