Glad you had fun on the swings!!!
Sounds like fun!
I do something kind of like that while on a plane or in the car.
I position my seat back slightly,
and sit up straight- but a little reclined back (still sitting straight)
you get a good ab workout in when
you are forced to contract your abs to keep your posture
as the car/plane is taking off.
Sounds silly. . .but try it!!
