It sounds like you want him to walk how my dogs walk. Lewis did this when we got him (he was too afraid of the world to stray far) so he's no help

But I did have to teach this to Holly. I will tell you the whole story of how I taught Holly, keep in mind that I did make a big mistake and would do it a bit differently now (mainly just not make the mistake) I used a clicker at all stages unless stated otherwise:
I started to teach Holly loose leash walking when she was a puppy (about four months old). I decided I wanted her on my left side, with the leash loose, she would be allowed to move a maximum of about 1 meter to the side away from me (so she could easily sniff fences etc if she wanted) and could move so her collar is about 40cm ahead of me (so part of her body was still over lapped with mine) and the same for behind me, she is not allowed to cross in front of me. =
1. Define the behaviour you want.
I started to teach Holly the position at home first using lots of treats, without her leash, in the kitchen (low distraction) then in the backyard (higher distraction). She was looking at me while we trained (I fixed this later, after another problem occured). =
2. Teach the position.
Then I took it outside to the footpath (with leash, Holly never cared about the leash so I didn't really need to learn to accept it/not bite it - I guess this is the same with Brody at this stage). All I did was really short walks (up and down the same street outside our house - although we don't live on a very quite steeet, Holly could handle it) with lots of treats, each training session like this was just a couple of minutes. Did this a couple of times a day, only when I was feeling patient and was not in a hurry (this was easier with a puppy that couldn't be walked too far anyway - it might be trickier with Brody).
= 3. Add distractions, practice the behaviour outside of the house, try not to let the dog practice the wrong behaviour.
Then I made the walks longer (up the street, around a no-exit street and then home again). Don't worry if the dog is "too focused on you" that can be fixed later.
= 4. Add duration.
It was all going well up to this point but then I kind of screwed up. Because Holly is very short I was doing a lot of bending to give her the treats (not fun as the walks got longer) and she still had needle puppy teeth which were shredding the ends of my fingers I decided to be a bit lazy. Instead of handing her the treats I decided it would be alright to drop them in front of her so she could get them herself (I wouldn't have to bend and my fingers were saved - I think I even saw kikopup do this). DO NOT DO THIS. She got really good at picking the treats up while walking (barely missed a step) but she also learnt that the ground has food on it (and not all of it is food that
I put there), it also meant that she walked with her head down all the time searching for food and was able to pick stuff up without stopping so I didn't notice straight way (although she was in the right place

).
I had to fix this. I had to start treating her for having her head up. I gave her treats for looking up at me. But this resulted in her going for walks looking at me the entire/most of the time (not want I wanted and not what you want from Brody either). If you teach Brody this way you might have him looking at you just due to the treats (without the mistake that I made) so I'll make the fixing of it a seperate step.
= 5. Realise any mistakes.
To get Holly to stop looking at me so much I basically just clicked everytime she looked away from me (she couldn't keep looking at me the entire walk) and gave her a treat. For a while after the treat she would keep looking at me, I ignored it (and didn't keep looking at her back - look straight ahead) until she looked at something else again.
= 6. Treat for looking at other things.
Lastly I mixed it up by sometimes click/treating when she looked at/sniffed stuff and sometimes when she looked at me and sometimes when she was just looking straight ahead. Then faded the treats so she realised that it is only the position I'm treating, I don't care about what she looks at. I also sometimes said "yes" or "good" rather than clicking so that I could eventually stop taking the clicker on walks but still had a way to mark good behaviour (I still take treats though - mainly for recall).
= 7. Generalise the behaviour.
Notes: At all stages I let Holly stop to sniff things. If she was heading over to something I followed her while keeping the leash loose. When I decide she has sniffed long enough I say "let's go" and we continue our walk (sometimes give her a treat if she stops sniffing really quickly - she can be reluctant sometimes). I still do this. I don't let her sniff things at all if she tries to run up to it/drag me over to it.
When we cross roads I do not make her sit (I tried it for one walk and found it very annoying), but she must stop and stand next to me until I say "ok" and we cross.
When walking past other dogs going the other way on the same side of the street I often ask for eye contact from Holly (especially if the other dog is not walking so nicely). Since I walk two dogs I can't have eye contact from both but Lewis doesn't want to greet other dogs anyway so I don't have to worry about him trying to say "hello" to them (whereas Holly would cut in front of me to greet them if allowed).
I didn't use any no reward marker. I think I sometimes stopped walking if Holly was being really naughty but not often. Usually only after putting her back on lead after being off at the park as she would still be a bit excited and want to pull so I would stand still until she calmed down (I don't need to do this any more). If the rewards are really frequent at the start the dog does not have a chance to get ahead so it doesn't need to be called back (worked for me and Holly anyway). Fade the treats slowly. You can't fade them too slowly.
Well, that was a long post. I hope you find it useful.
If you decide to teach Brody the way I taught Holly then keep in mind that it will be different for you. I was training a puppy that hadn't practiced any other kind of leash walking and she was never reactive. You will probably have to add/modify some things.
Be very patient. It took months before I stopped regularly giving Holly treats while walking (I rarely give them now though - except for recall).
Don't decrease the reward frequency too quickly.
Have fun.
