I keep on learning new skills!  But, once again, the skill of applying the leg aid it is not as easy as it sounds.   We started by working on my seat.  Then we focused on my legs.  After all of my body parts were moving in concert with each other and following my horse’s motion, I could concentrate on closing my legs for a canter leg aid.  For me, it helps to feel like I wrap my legs around my horse’s barrel and pick him up under my seat using my legs.  Now I feel like I am making the canter happen with some control over the length of stride and activity vs simply following the canter.  I have leg aids in canter!