When I warm up before schooling a horse on the flat, I tend to do it in stages.
First, if I have the opportunity (say it isn’t freezing out, or pouring, and I have a place to do it), I go for about a 15-20 minute walk, loose-ish rein, just to let him/her move.
Then I trot, again, long-ish reins, canter up off his back, get him thinking forward and letting him put his head pretty much wherever he wants to, and then let him walk a bit before starting, as quietly as I can, to “put him on the aids.”
By this point I may have been on him 25 to as much as 35 minutes—a long, slow warm-up. I didn’t used to do this. I would come to the work area, walk around for the obligatory 4.963 minutes, pick up the reins and ask him to get to work.
© Tamarack Hill Farm
The slower way is better. Better for his mind, better for the elasticity of his body, better in 101 ways. He does’t assume that the moment I sit on him that it’s “grind time”, and I feel that all my horses today are less worried by me than those I rode “back in the day.”
Just another example of the saying, “I wish I’d known then what I know now.”