When I think of someone in my life with the highest credibility, my swing coach is pretty high up there. He is one of the most knowledgeable people I know when it comes to the fundamentals of the golf swing. Anytime I am in a low spot with my golf swing, I can always rely on him to get me back on the rails. He is almost always available when I need him, and I am very grateful for him.
I do not personally know your golf coach but based on your ability if you trust him then he must be credible.
Great example, LIVE LAUGH LOVE GOLF!