Need help with training motivation

For those of you who do a lot of training or have been in training for a long time, how do you keep yourself and your dog motivated?

We go to class every Saturday and Sunday and have been for sometime. The Newfs are fairly new to formal classes so they are still pretty enthusiastic. Ursa, on the other hand, seems to be suffering from burn out. Yesterday was her first Advanced class and even our trainer noticed that she just wasn't into it. We've had this problem at home off and on (not surprising given her age and her breed) but this is the first time that she mentally checked out during class.

Part of it may be that we have taken off the Gentle Leader in preparation for her CGC training. She seemed to associate wearing the GL with working. She's never worn the training collar during at home training though and we've had the problem here.

I can see the potential for Fargo to have the same problem down the road as he gets tired of training about 3/4 of the way through every class. Once he's decided that he's had enough he isn't exactly the most cooperative dog either!

Taking a break right now isn't an option. Our trainer will be leaving in the spring to get married and will be taking some time off herself so we want to finish all of our basic classes with her. We've had trouble finding another trainer that likes working with the giant breed dogs.

Any suggestions on how to keep everyone motivated?

It doesn't always work, but sometimes with Jake, taking a few minutes and just really roughhousing with him will get him back to a frame of mind, where he is focusing on me again.  When I say roughhousing, I mean where he is leaping into the air to try and body slam me.  I turn at the last minute and he goes by my shoulder.  Using a high pitched voice and lots of quick body movements will get all my dogs, other than Cody, going.  My energy level gets theres up and they pay attention to what I am doing.  You have to keep the energy up, while maintaining some kind of focus, which isn't easy, but is better than a roadkill imitation.
Kathy