How do you make a horse do a collected canter?

Ask the horse for a regular canter but keep the reins short. Apply leg. Gently squeeze and cluck and you slowly shorten the rein a bit more. Or just do a half halt. Then sit deep and relax. Do not release leg until you feel like you have ur horse going. In every corner and squeeze. Always have loose reins when you start. I mean keep them not long but not too short so you have something to shorten.