He looks like the sweetest dog Stacey! I hope he has many great years with you and your family.
A word of caution as far as the pulling thing, even on the merry-go-round. Pulling and playing tug can be very hard on the hips, elbows and shoulders of a young dog and can cause problems down the road. I don't let my GSD's overdo anything until their bones are fully developed. Doing high agility jumps before they are 2 isn't recommended either.
I like to take mine swimming. Throwing a ball and frisbee into the water is a lower impact way of excercising them and my dogs can't get enough of the water. Water wears them out fast too! :D
Most of all just have fun and enjoy his youthful exburance!