I guess I should mention that I don’t know Bob. Peter, my husband, knew Bob in high school. To be perfectly honest, I’m not sure Peter and Bob were even close pals in high school. But Bob sent me a Facebook friend request shortly after he became Facebook friends with Peter and, even though I don’t know Bob, I accepted. Then Bob challenged me to do push-ups. “Join me in the pushup challenge!” Bob said. I was delighted that I had been invited. I love the idea of a personal trainer—although I am far too cheap to hire one. Here was ...