Try roller skating and falling flat on your face!
You'll know you really got a truly good work out when you notice the dried blood on your left knee cap, and you can hear all your joints squeak at the slightest movement, and each muscle aches just thinking about walking from one spot of the house to the other.
Really. You gotta try it.
And yes, that is yours truly.
At least my son had fun at his birthday party! That's him in the back with one of his friends. :)