There are few things worse than having a horse who doesn't want to respond when you ask him to. While ideally I'll be using my seat and legs 1000x more than my hands, responding to the bit or hackamore is still essential for the horse to understand. That's where we begin.
We've talked a considerable amount about lateral flexion and what it means in comparison to vertical flexion. While keeping in mind that a headset is not collection, which comes behind, we still want our horses to soften in our hands and give to the bit (or hackamore). One reason is, especially when working on our suppling exercises, we want the horse to use his body while following his nose. It's really that simple.
To get started, we'll ask for a nice walk with long and low carriage and a lengthened stride. I don't want to even ask for anything remotely resembling a headset for a little while, at least until I have a relaxed and forward walk, then a quiet halt. At that point, I'll pick up my inside rein and request just a slight give. If the horse resists, I'm going to hold light yet steady pressure until I have the slightest response. Repeat toward the outside.
Next, we will walk forward again and I'll ask for the same only slight bend. First to the inside, then to the outside. All I want is the horse to respond when I pick up each rein, inside then outside. Any resistance is met with only light steady pressure until there's the tiniest bit of give. Now, ideally the horse is going to begin giving to the bit as soon as I start to lift my rein and not wait for pressure on the bit itself. Lots of praise follows that response.
When the horse consistently responds the exact same way every time I ask ,both at the halt and at the walk -- it doesn't need to take all that long to achieve -- we'll start trotting while asking for the same give. At this point, I'll have the horse halt again and introduce the concept of taking hold of both reins simultaneously, then asking him to give vertically. We'll then repeat the same steps both at the walk and again at the trot.
Once more I reiterate, what I'm asking for isn't a headset, it's a reaction and response to rein pressure. I don't care so much if the horse looks pretty at this point, my goal in the earlier stages of training (or retraining) is self carriage and a responsive mount. This goes for any discipline the horse will ultimately have as a primary job.
Without flexibility, willingness and responsiveness, riding and enjoying that horse will be an uphill battle. I like my horses to be willing, flexible and responsive. From there the horse can go in any direction, and it doesn't matter whether he's a trail horse, a cow horse, a pleasure horse or performance horse. Foundation is the key!