Good, basically it’s the same rules for a human wanting to gain muscle. Increase your vitamins/nutrients & exercise daily. I don’t know if it’s the same vitamin for dogs as it is humans but the B vitamins are the ones I’d try first. They
I advise against the puppy pee pads!! It will encourage them that it’s OK to go inside the home, which defeats the purpose of house breaking. Once you form a set of rules you have to stick with it, and POSITIVE REINFORCEMENT!! Don’t rub the dogs nose in it, and beat him/her. Take them outside and wait until they go and give them treats. They love treats and praise!
Try vitamins. They should help with her energy levels and put some stock to her. As far as the walking, try upping the time in small incriments(sp?) Do they have a dog-park anywhere near you? Time at the park is great, it gives both exercise and much needed socialization. Hope this helps.