Train for what you want them to do - not for what you don't want them to do

Recently I was contacted by a past client who had moved to a neighboring city and he was having trouble taking his 4 year old terrier poodle for walks. The city had designated 20 or more kilometers of bike, walk, run, skateboard etc. which is closed off and vehicle free area on Sundays. Perfect for long and pleasant dog walks. The problem was, the man's dog had developed a serious mad-on toward skateboards and Volkswagon Beetles. Yup, all 35 pounds and he was going to disembowel a VW. The man was coming to our area for a week and he wondered if I could do anything to help him.
We arranged times and I had 5 one  hour sessions free and the challenge was to redirect  Rambo's thought process so his retired and slightly aging owner could enjoy the great walking area.
The first thing I did was pick up the dog and set off on a one hour walk through a residential area that was quiet and progressed toward more traffic and active areas with more distractions and hopefully at least one VW. As luck would have it I had one go by quite quickly and "killer" hit the end of the leash barking, snarling, and teeth flashing, in his best "let me at him" fashion. I just stood still until he came back to earth and went on our way but my mind was starting to assess this challenge. The normal trainer's solution is to present the problem over and over and correct the dog until he hopefully decides he should quit attacking VW's or his neck is going to get pretty sore. I don't subscribe to that method because my goal is to find positive solutions so the dog is happy to repeat his successes instead of dreading his failures. Besides which, the owner wasn't going to be able to jerk Rambo over backwards without  doing serious harm to one or both of them plus all this was going to do was make the problem worse. Well this sounds easy Tonto but how are you going to accomplish it?
Next day I showed up equipped with a flat collar, no choke collar or anything similar plus a pocket full of super tasty high value treats. We went a half block away so the student wouldn't be distracted by his owner or their environment and I started at square one just like I do with a puppy. I moved him left and when he followed my hand I opened it and gave him the reward. After about ten of theses I moved him left and right and then when I stopped I lured his nose between his ears and toward his tail and said sit. He remembered his old lessons very quickly and was sitting and doing a sit, down, and stay with "lures and rewards" at least 8 or 9 times out of ten so I decided it was time to proceed to phase two.
I had about half hour left which was just right for a training walk which is different from an exercise walk. We proceeded down the street and as soon as he got out of position I said Oops! and stood still. At first he was confused but he eventually came back to me and was rewarded when he assumed a sit near my left side. It wasn't perfectly in position but I could work on form in some future lessons. From then on we progressed to fewer errors and more relaxed time in the proper heeling position and I was looking for an opportunity to use our new skills and very shortly a somewhat noisy dog bolted toward us and before Rambo could react I stopped suddenly and gave him a sit command both with hand signal and vocally and he was sitting politely beside me as the noisy one came up , sniffed, and decided there was nothing here for him so he was on his way. Good dog, extra reward, and away we go. Lots of cars went by but nary a VW and I was about to give up and about quarter block away, behold a shiny green VW monster was driving into it's driveway and killer was switching gears faster than your best NASCAR jockey. Before he could hit the end of the leash I was into the Oops! routine and standing still armed with my trusty "lure and reward". Hooray, the light went on and his butt hit the sidewalk and I smothered that little sucker with a handful of mind altering treats. And then something interesting occurred. The driver turned the car off and Rambo relaxed. When I saw him let the air out of his tires I asked for a down stay and dropped his leash beside him to see if he was serious. Sure enough no problem. From this I was able to figure out it was the whistling sound of VW's that was inciting him. Hey, great gains so we headed home winners and we had only finished day two.
From here on in I forgot the VW's and skateboards and devoted all my effort to building on the positive and perfecting his manners and leash skills in as many different environments as I could find. The more activity and distractions the better, we were on a roll and he was getting all his old skills back plus some new ones. By the end of day four I was confident in asking him to sit stay in most any situation and as long as it wasn't somewhere that could endanger the dog , I'd drop the leash and walk a few steps away and back and forth in order to help him to understand that he had earned my trust and I was satisfied that he was comfortable with our situation and environment. Next, train the other end of the leash. When I returned the dog I asked the owner if he could take time to join me the next day and he agreed.
Next day as soon as we left the yard I handed the leash to the owner and gave him a short refresher on positioning, looses leash, and confident heads up presentation, and away we went. In the first block he needed to remind the dog who was in charge with a quick correction, an Oops! and an appropriate reward probably a half dozen times but  it wasn't long and the two of them were proceeding like old pros. I headed toward a busier area and I could sense a bit of apprehension but I didn't utter a word. I figured as long as the dog was going along properly I'd let the owner work things through. It wasn't long and the pair were going along great with the dog on a loose leash beside the owner and as we came to busier areas they were calmly waiting and giving way to groups of people.Next came the big test. It was market day with two blocks of booths and every kind of distraction you could conjure up. I  told the man I wanted check on something and
was he up to taking his dog through all the noise and crowd. He got a big grin on his face and said "Heck Yes". From there on it was a snap. The dog and owner had discovered a whole new world.
I'm pleased to report that they are enjoying their walks and ignoring skateboards and VW's.