Walk with me:
Description:  this exercise is taught for two reasons.  1) nobody wants to keep their dog on a military heel all the time.  There are times when it isn't necessary or wanted.  2) this helps to get the dog ready for the heel exercise later on, by teaching him how to politely walk on a loose leash.  This exercise will teach your dog to walk politely, without him pulling you or you having to drag him, and make walking him much more pleasant.  

Action:  Have your dog on leash and start walking.  If your dog gets to the end of the leash, stop walking and call his name.  As soon as he turns and the leash goes slack, then click and treat.  Start walking again and do the same thing.  In this exercise, your dog can be anywhere around you, front, back, left or right as long as the leash is loose.  Eventually you will want to "shape" him around to your left side only, as you get closer to teaching the heel, but for now any position is fine. When you get ready to put this behavior on cue, you can use commands like "lets go", "lets walk", "walkies" or whatever, but try to keep the word(s) simple.  

Start out by getting the dog to walk with slack in the leash just a few short steps, remember baby steps are the key to successful behavior.  Then gradually increase the distance he has to walk before you click and give your treat.  Eventually you should be able to walk great distances with your dog neither lunging or lagging.  

Tips: If you have a very strong minded dog, you may have to do a good deal of shaping to get him to walk on a loose leash.  Start rewarding him for just looking back when you call his name,  then go to rewarding him for looking back and taking a step toward you.  Then for looking back and taking several steps toward you.  Then for walking on a loose leash all the time.  Be patient and break the exercise down into simple steps.  If you get frustrated, go back to something you KNOW the dog can't get wrong, reward that behavior and then end the session.  Pick it back up later when you are more patient.