Just something I've been thinking about is how to encourage my horse to have a more 'active' walk. I mean, when he's keyed up because we're doing interesting stuff (ie. "exciting" jumps), he tends to do so of his own volition, pushing from behind and being more better, so to speak, at walking.
But other times, if we're just going into flatwork and before we've done anything to get him really interested...he kind of trudges.
I'd like to encourage him to walk more actively all the time, but I don't want to nag, necessarily, with the 'push alternately with each leg' thing an old lesson barn taught me. Also, I don't think he really "gets" that anyway.
Go study Nuno on youtube. He's the walk master.
I do 15 minutes of ribboning walk work before anything else, every ride. Transitions, shortening, lengthening, all the lateral work, gerivolte, pirouettes, school halts.... then collected canter to long and low canter, to long and low trot to raised trot, then off to work we go!
I find that it's very important with horses that are naturally "low key" in the walk (avoiding 'lazy'!), to never let them amble in any situation. If you are hacking out, you do so with a forward marching pace. If you're walking to the school, same thing. Walk break mid-session? Same thing! The horse must understand that when you are in the saddle it is time to be motivated. Having said that, you can also set him up for success by, as Merry suggested, figuring out the best routine to loosen/warm up/and inspire him, and you may well find that some initial trot warm up is necessary to get him activated in walk. You might add in some simple cavalletti work, or opt to school longer walk sessions outdoors.
I never let a horse trudge under saddle. They can trudge in the pasture. Under saddle, they're expected to work. You don't nag, they tune out to nagging. And if they tuned you out you're totally ineffective. You tell them with certainty - go forward at the walk. Now. That is a tap or a snap on the hind end. Then calm. Move forward. Always. well spaced walk poles help because if they amble over them they'll trip. I'd say you have to set your mind to making your horse move forward off of clear aids. You can teach this on the ground on a longe line. Or you can have someone experienced longe you and keep your horse forward. 45 min of work out of 24 hours of ambling isn't too much to ask if your horse is in any kind of shape. If he's not, then expect 30 min of work. Or 15. Give him breaks but don't let him take over your riding session.
I ride a horse that tends to be lazy at the walk, so I try to focus on having an active seat & hands that are moving with the gait. If I faze out & stop doing this, I realize she has lost impulsion when I tune back in.
If your horse has truly lost the zip in his giddy-up, try a few prompt trot/halt/trot transitions. Wake that pony up! Added benefit: you're reinstalling that GO MEANS GO when you return to the walk. Transitions of any kind (direction, gait, bend, stride length, etc) will help, but sometimes schooling ad nauseum in the walk makes the walk worse.
I also second (or third) keeping things active even when on breaks between schooling sessions. And if things get too lazy you can still do walk/trot/halt/reinback/trot/walk (etc.) transitions whenever you don't get the "Yes, Ma'am!" response you want. As always, consistency is key.
Most of my horses have been "low key", lol! I've found that getting them out and about, or maybe just doing something new (like kicking a ball around) gets them fresh again and we can go back to much more productive work with a fresh, eager attitude
My trainer and I just added ground pole work to our lessons. We started out with walking over a ground pole in a figure 8 pattern. However as we approach the pole I'm supposed to identify what let he is stepping over the pole with and if necessary make him stride out to step with the appropriate leg maintaining the correct bend. For example if we are tracking right we straighten to the pole and we are going to turn left so he should cross the pole with the left front first. When we began the exercise he was short stepping his approach to the pole and lagging after. So I would apply appropriate leg to encourage his to step further forward with the correct leg. 10 minutes later my horse was literally sashaying around. Lose back connected walk with purpose. It was super beneficial for us.
--Luck is what happens when preparedness meets opportunity--
I always warm up under saddle by walking out on a long rein the full length of the arena in both directions. If the horse slows I give a quiet leg aid and then a brisk tap if there is no response.
NO Fidgeting! That nice free, forward walk on a long rein at the beginning of each ride sets the tone for a good walk. Then pick up the reins and do it all. Do not fuss with the walk. It is the easiest gait to trash.
“Reality is merely an illusion, albeit a very persistent one.”
? Albert Einstein
Not about how to improve the walk, as everyone has offered good ideas and suggestions so far.
Instead, a comment, from observing and sitting beside judges when being a scribe, It is remarkable how many people throw away marks by producing a poor quality walk in a test. 'Crossing the arena on a loose rein at a walk' does not mean shambling along and taking a breather. Very, very few people seem to walk with purpose. It is an easy place to collect marks.