if you google search weight pulling they have a lot of information... but.... i am sure you know...some is good and a lot is not! But that is the internet for you. I would not start out with a gallon and rocks, just because of the noise could be terrifiying at first. cooler type container that you could put water in and drag. that noise would be a little quieter, and then work your way up. And for the harnesses, make sure that it looks like a sled harness type...just make sure that the weight is being pulled by his chest (i think, still learning) verses his back...Also something that might help, bring to the chiropractor first to align the body and mind first. Also to fix any issues that might be. If you want...i would get xrays to see how the hips look and how the knees and elbows, so you don't have a hip in a shallow area. Also,,,, add suppliments and extra exercise..like a backpack on his back to help begin to strengthing the muscles. there is a lot of conditioning before you do anything!!!