Are you already a personal trainer adding on a well-coaching certification on top of that, or is that going to be your main certification?
My thought would be to set your prices based on slightly below average in your area. Let’s say in your area that’s $50 an hour. If you’re going to give a discount to get practicing, don’t say your price is $40 an hour. Say that the first 10 clients will get a discount of 20% off of your regular hourly rate of $50 per hour. That way, you’re not permanently stuck at $40 per hour.