Rent-a-Sibling.com?

I spent the past 4 days with Frankie morning to night. I'm now sitting in front of a tv in pain. Feeling a bit bad about her not having a sib (or a younger father), I treated her as a workout buddy and tried to keep up . . . for 4 straight days. We swam for hours, ran stairs, played a lot of Uno (but they were fast games), walked lots (with her on my shoulders) and snacked all over the city. Lots of fun, but I feel a bit old. At least I don't have to worry about missing the gym this week.