Not only does a group on de-value your services, but I worked at a facility that offered it, we had 6 hour shifts in which we were paid minimally to work with clients. The entire shift was back to back first timers to Pilates. It was equipment private sessions that were offered. No one had a good experience, not the client, nor me, as an instructor. Anyone offering a training service should not offer discounts, or agree to teach under a groupon circumstance. I feel my education and my craft is worth far more than a quick sell.