If you have a horse which is quite unbalanced through the trot-canter transition, and either wants to run into the transition, or pulls themselves into canter, this is a simple exercise to help engage the hind end and get them stepping through into canter.
Initially, do several trot-walk-trot transitions, making sure walk is clearly established for 4 or 5 steps before trotting again. Then do the same, but as you come back up into trot ask for canter almost immediately.
As the rider, you need to make sure you are completely balanced and not influencing the horse negatively by tipping forwards or back (we’ve got a tip for that too, so keep your eye on the site!).
You can vary this by having a line of trotting poles and asking for canter over the final rail – the poles help engage the hind end and make sure the horse is stepping through.