Those of you who say you don't canter in a zig zag between trees and other things along the trail. Probably don't run barrels or Poles in an arena either. I don't see a lot of difference between running poles at a 4H event or zig-zaggin thru the trees in a forest. Heck we do it all the time, especially when we chase cows.
When I get a froggy horse, I put him to work dancing with the sagebrush or what ever other bush I can find. The horse has too much energy, Its a great way to burn some of it off. The horses doesn't want his legs in that crap any more than I want it brushing me out of the saddle. A few minutes of dancing with the trees will take the piss and vinegar out of most froggy horses.
I put them back to the trail and as long as they behave, I let them walk down the trail. If they get excited ( herd bound for their buddies, wanting to return to the trailer, upset about not being the leader, You insert your problem here) We go back to dancing with the trees at a trot or faster. Those horses learn real quick they get to rest if they behave.
Horses were a midlife change for me also. Skiing, Motorcycles, Fast cars, basketball and other sports consumed my younger years. I got into horses when I finally learned how to kill elk and found out how hard it was to haul an 800lb elk off a mountain. I quickly learned that I couldn't just use my horses for a week or two of hunting in the fall, They were a life style changing event that required a lot of time and new learning.
I've Seen my horses slip and fall in the pasture when they get fooling around. Usually slipping in wet grass or mud. I've ridden some of the roughest country around and twice in 20 years have I gone down with my horse. You know what? Some times a horse just slips and goes down. Walk or trot, sometimes it just happens. Sometimes we get hurt when that happens, sometimes we brush the dust off and laugh about it.
This was the 5th horse in a line, The first 4 crossed the water, The 5th dropped out of sight in the quicksand. See the wet sand all over the horses hand and front quarter. Rider when splat over the horses head flat on his back in the stream. You get back on and finish the ride.