[Nismo]

I have always wanted a really muscular boxer and I was wondering if any of you have put your dog on a work-out program of some sort. I have heard of making them drag a big chain but that does'nt sound like something that I would want to do. Is that wrong or normal? Is there any side affects to having a muscular dog? I don't want to attempt anything if it's going to hurt him. Any thoughts?