✔ 最佳答案
And your question is?
Obviously he's a very submissive dog, which is genetic. Genetics can't be changed. Thankfully he's not aggressive.
Then stop taking him there. Dogs don't need to go to camps and/or Dog Parks*, period.
Your responsibility to provide his daily walk/elimination times, aerobic exercise, such as playing fetch, and mental stimulation such as obedience training.
Just feed him properly*, forcing rapid growth will cause more harm than good, and will not change his genetic makeup.
*
http://i40.photobucket.com/albums/e224/GLLNTKNIGHT/feeding_zps90a9666f.jpg