WII-FM: "What's in it for me?" is written in invisible ink on your horse's forehead! In my Natural Horsemanship with Heart training program, I encourage students to always consider their horse's point of view when teaching, riding, playing or just hanging out with their horse. And when you know what's important to a horse (through understanding of horse psychology), it's easier to know what things your horse might enjoy (apart from the obvious munch on a favorite treat or patch of succulent grass!)
This is why I love WERPs so much (Walk, Eat, Ride, Play). We take outings that involve some walking side by side, some eating (some trailside picnics for both parties), some riding, and some playing (ground games). We both have fun and your horse will be a much more willing participant in your activities when next you call them up from the paddock!
One of the best, simplest pieces of motivation for your horse is a good scratch! Sometimes in clinics when we play the Touching or Getting Friendly Game, I hear that 'my horse doesn't like to be touched or brushed', however after a few minutes of experimentation, we find that the horse does in fact love to be touched and groomed, just not in the way that their human was doing it! Horses, like people, are individuals, and have individual likes and preferences. What is a wonderful scratch for one might be irritating for another. But when you can read your horse, and importantly allow them to stand freely so they can 'talk' to you, you'll be amazed at how much they 'tell' you! One of the easiest words to teach your horse is 'Scratch'!
I stand next to my horses, my scratching hands at the ready, and say the Scratch word, and they will reach their head around and nip themselves where they would like it! You can be useful to your horse, and WII-for you? The joy of seeing those curled lips, the outstretched neck, the expression that says, 'oooooh yeahhhhhhh'. I've yet to see a horse lover who doesn't enjoy such a moment!!