Dog training

I've been doing some dog training lately using the clicker and broken up pieces of Pupperoni dog treats. The two pups, B and D, have already been training so they're familiar with the following commands:

• Sit
• Down
• Stay
• Shake, Other (B can shake with both paws)
• Come
• Beg

B is marginally able to Heel, however D goes nuts on walks - barking and dancing like crazy- then running out of steam after a half-mile. I'd like to calm him down and increase his endurance for walks, however, extending the duration of a walk is difficult as he has a thick fur coat and it is summertime. So it will be a careful balance and constant monitoring to make progress in this area.  

During my last visit, B learned how to Spin and she has managed to remember it. 

D is now learning Spin (as he has forgotten it) and enjoys it, but has a hard time concentrating during training. (For training, I isolate them when the owner isn't around). B is working on moving from Down to Roll Over, which is a big exercise in trust for her. She hates being picked up and isn't much keen on my rolling her over, so it's a gradual movement. 

Looking forward to working with these stellar dogs this week.