At this point, I suspect you are dreading walkies, and he is picking up on your emotions. So you have to get BOTH of you happy and excited about this idea of a new walk, lol.

Check where other dog walkers let their dogs stop - then make a point of letting your dog stop to pick up 'p-mail' at those locations. This gets his senses interested in the new smells.

Are you walking with an ipod / music source / talking on the phone? Don't! Keep your focus on the area around you, and your dog.

Change your pace. Walk 5 long strides straight ahead, dart to the left for 4 fast almost running steps, back up calling him to keep up with you. (Watch the traffic when you do this!) Make YOURSELF interesting, so he has to keep focused on what you are up to, what you are going to do next. You may not get far doing this, but you will cover ground and get his interest.