Quote Originally Posted by flip195
15 mins a day sit heel work, in an enclosed area,

until he got it right,
make the dog sit when he does praise reward,
Take one step with the heel command and sit again & reward.
Gradually increase the steps taking always start and finish with sit.
start and end training with a game... make it fun... never work more than 15 mins at a time.

German shepherd should pick it up in about a week of 15 min sessions max.
Tried that, all last summer. Pretty much exactly as you put it (I did a lot of reseach). He was already 4 when we got him, and not at all well behaved. I worked with him a ton in the back yard. I even used treats (or tried, he has absolutely no interest in the treats when we are outside). Tons of praise, about 15-20 mins per day for 3-4 months. It did nothing. At the end of summer, I had to take him the the vet. I opened my car door, holding onto his leash. He jumped out of my door and took off - with me in tow. I ripped my jeans, scraped my face. At least I held on to him, because he has taken off before and he can be difficult to track down. I went in to the vet's office and asked for a recommendation for a trainer. Roscoe went through 8 weeks of training with a prong and graduated first in his class.

I know I went off of the topic of shock collars, but I think that the 'don't use something you wouldn't use on a two year old child' was not good advice (what 2-year old weighs 93 lbs? ). And you cannot generalize the breed, especially considering he's a mix. So what would you have done? Work with him another 3 months and hope for the best? Or take him back to the shelter? Sorry, but neither was an option.

EDIT: I should also mention that distractions made it extremely difficult to do the work you mentioned. He always wanted to chase the birds and bunnies, bark at cars, etc. Perhaps anything more about this should be said through PM, as I do not wish to further hijack this thread.