They are very hardy, driven, and good athletes. Musher families often have many dogs. They think of their dogs as trained athletes, family pets, and friends. The physical traits and muscular structure of the dog's body are important, but the best dogs are the ones with heart, willingness, and the desire to get the job accomplished.
Lead dogs show signs of being leaders from puppyhood.
They are usually very curious and spunky. As they get older, they show that they like to be in charge and can learn the commands very quickly. If he doesn't, he's just not going to make the team. No Cinderella stories there. Beyond that, it's mostly attitude.