Revving up the engine

I believe that my next big riding hurdle is to learn how to rev the back engine. I can't ignore the symptoms anymore - when I rode Charlie while Shannon was on vacation, when I rode George while Mike was on vacation, whenever I ride Willig, and this week, when I rode Charlie all week - he was sputtery and slow by the end of the week. It is pretty easy to get the nice movements when I have the engine revved up, but I'm not very good (and maybe that's even being generous to myself) about getting it revved. I started my lesson with Shannon showing her test 1-3, and what I thought was wrong with it (at the canter, his nose was going up in the air, but if I tried to get him on the bit, he'd do a down transition to a trot). And the cause was, as you probably guessed, the sputtering. The way we worked on it was lots of transitions. Halt to canter back to halt to trot, and then lengthening and collecting within the gaits. My instructions before the show today were to do about 5 minutes of loose rein walking and bending, and then the big, confident, assertive transitions to get the engine going for less than 30 minutes. Which we did. And had a nice ride. But this is still a bit out of my grasp, so I am going to need to think more and talk more and ride more on it in my lessons - I think it's a very deep habit that's going to take some real effort to change, but I think it's my next big step to get to the next level of riding.