Does your dog pull a lot on walks? Get really distracted by squirrels or rabbits or other dogs? Maybe your shoulder hurts from the pulling and you can't focus on a conversation with a friend while walking. You wish that you could take your pup with you to enjoy parks or trails or other populated places, but you're nervous about your dog's safety should she pull too hard for you and you can't control her.
Or maybe you just got a puppy -- congratulations!! And you want to know how to start the good walking skills early on because let's face it, it's SO much easier to start good skills when they're small and can't hurt you on a walk! Try starting leash walking training with a 90-lb ball of furry energy that can yank you down the sidewalk -- it's so much easier to start when they're little, I can tell you from experience.
Or your family member just got a puppy and you want to give one of the best gifts ever: good leash manners. :)