Yep just hold the treat in your hand so he can smell it, hold it just in front of where you want his nose to be, so you are effectively positioning him in the right spot and walk. If he's like T he will follow obediently, looking up at you every now and then to see when you are going to relent and give him the treat.
Like ToddW said change your direction often, do about turns eg. turn 180degrees and go back where you came from, 90degree turns both into and away from the dog, find some poles a little way apart and do figure of eights around them, all those sorts of things will keep his focus on you and your body position.
I can't let T see the treat otherwise he gets too excited and does the "vertical poodle" and won't heel but ends up jumping in the one spot :rofl: but if your guy needs some extra enthusiasm show him the treat. If he isn't food motivated a squeaky toy works just as well.
Edit to add - you don't have to have the treat in your hand forever, just till he gets the hang of it, then put the treat away and keep your hand in the same spot, then after a while remove your hand and put it how ever is most comfortable for you. Still treat often in the early stages, just hold the treats in your bum bag instead of your hand :smile: