do lots of turns and serpentines, changing directions a lot to keep their mind working and engaged. I have a horse that gets distracted and this helps him a lot!
Very interesting answers! Thank you all!
very often, I think at least two times during a ride, once I was even going under him.. he was visited by a vet but no problems found!
Maybe do some pole work or something to make him look and think about his feet and puck them up. You could also do some small cavalettis too?
How much does he stumble? This could be more medically related and less a training issue.
Ask for more, like transitions and circles just to keep them interested and listening. Halting every so often helps with that too, I did the same with my boys
Keep him busy with a lot of transitions, this helps to keep him alert and focused on you. Try to make him do something else every couple 10 metres when warming up. For example walk, halt, trot, extended trot, normal trot, walk, and so on. With my horses it really helps a lot to keep them focused!