Over the years of giving instruction and the thousands of hours of lessons, one of my largest takeaways is the importance of trusting the process. Every client is unique and has a very different set of needs. When prescribing a mechanical change it's important that you believe in the drill, and understand that the results will not always immediately reflect what you are attempting to change. This is especially prevelant when the change you are asking them to make completely counters the mechanic already in place. Coaches will often stray from their logic and apply "bandage" mechanics to achieve immediate results if their client is having difficulty. A mistake I have no doubt been guilty of myself. This dilemma will manifest itself when clients expect to see relatively abrupt improvement. A reasonable assumption but often not acheivable.
As coaches it is our job to help them understand the change in its entirety. Explain the what, the why, and the desired results as well as providing them with a realistic time frame before noticeable improvement sets in. Help your clients invest in the mechanic by providing them with knowledge and a positive direction. Find ways during your sessions to take the results out of the equation until some mastery of the skill is demonstrated. Without having to focus on where the ball goes, it is a lot easier to focus on what's happening. If you believe in what your teaching and your client struggles initially with it, take a breath and trust the process.