You have to become the best thing in that dogs life. All fun, good, wonderful things come from YOU. Always have a pocket full of treats, I used Zukes tiny treats, reward the dog for all sorts of behavior you want from him. A couple of times a day do some OB work that is FUN, light and HAPPY. Keep a toy or two that is special for the two of you to play with, like a tug or ball, hidden away and several times a day bring it out and make it the best play time ever! Take walks alone where there are no distractions, where it is just the two of you enjoying the great outdoors. Go for rides in the car....alone, leave the other dog at home.
Good luck!