Apply gentle, consistent pressure as long as necessary until the colt makes at least a slight move toward where you want him to go (even if it’s just random at first). Maybe not even a full step, even just shifting his weight that direction. As soon as you get even that tiny bit of compliance, immediately release the pressure and reward him with a little break. Then after a minute, start the pressure again. Repeat. He should gradually start moving the way you want sooner and more easily as he learns that’s the way to get the uncomfortable pressure off. If necessary, keep working at it and start demanding a bit more movement before you release the pressure, then a bit more, and a bit more, and so on. Always reward by releasing the pressure once he’s met the goal you’ve set so far.

Never use constantly increasing or excessive pressure – don’t make a fight out of it. Just enough to cause very slight discomfort, and stay there until he does what you want, as long as it takes. Then immediately reward him by releasing the pressure. Also, never release the pressure before he does what you want, for any other reason. Make doing what you want the only way to release the pressure.

If you can do that with good consistency and keep doing it, it should work pretty quickly and painlessly, for both you and the horse.