@Carolyn Duffy Sorry for the delay! Somehow I missed this post, but I love this question because it goes with some other things I was just thinking about. The answer to your question is: "it depends". @Meredith Krause since this is your horse - you'll be interested in this too. I always start with using the seat and leg, see where that gets me and use the rein if I feel like I need to. Sometimes you need to use the rein initially just to train the response and then you can refine it with your leg. Here's where experimenting comes in (and I can tell you a story about this horse, in particular) because you want to try and determine what the root cause of the imbalance is and where it's originating. This horse "seemed" to be heavy on his left shoulder, but as I played with this exercise I noticed that he has more of a restriction in his spine or ribcage on the left side (or maybe the restriction is on the right side, so he uses the left 🤷‍♀️). That's one of those chicken or the egg scenarios! And, to make it more difficult, you also need to consider your own position. Many times our horses are compensating for us. That is why I like the experimentation. It forces you to move your body around and break some of the patterns you've learned. I would start with using your legs to move his ribcage over and then lift (and this is important) the right rein to "bend" more right. Then, drop the rein, relax your legs and feel what he does with his body. Does he just dump right back onto the right shoulder or do you feel the hind end or back/ribcage area come over first? It takes a bit of playing with to get to the point where you are feeling it reliably. You can also do the "correction" and then ask him to go trotting. Usually speeding it up exaggerates that problem, so it can be easier to feel. It may look a little weird, but it helps you learn the feel and helps the horse understand what you want. The hindquarters yield video is a good one to watch so you can get the idea of "lifting" the rein. Most people want to pull it back which just causes the neck to bend and doesn't affect the shoulder or poll of the horse.

@Carolyn Duffy let me know how it goes!

@Marjorie Lewis that is pretty common! Think about “titrating” your exhale for slowing down. It really helps refine your aids & remind you to keep breathing.

@Jennifer Wagner I was thinking about this yesterday as it’s such a normal thing. I call it the go, but don’t go conundrum. Definitely need to sit down & right about it!

@Isabell Bradley Nice! That's the one thing I miss right now, not having easy access to trails.

@Isabell Bradley We're on a small piece of property that is close to the road and most of the places around us are smaller without horses. We have lovely places you can trailer to, but I miss the days of just jumping and going for a hack. Now, it would take me about 5 minutes to walk around before I'd have to tackle the road - and people scare me with their driving!