Strength growth requires moving heavy things for a certain amount of times. Rest and repeat. Add variation when needed.

A coach is essential for maximizing these practices. And even coaches need their own coaches as well.

Good Nutrition requires being aware of what you eat.  Understanding food beyond the numbers of grams and ounces. And implementing a plan for success but allows the practitioner to make mistakes and learn from them. 

A coach can aid in finding where you can improve and how you can build a plan that fits your lifestyle.

These ideas are really that simple. Dietary science can make things as complicated as they like. Which is why a lot of us struggle with these concepts. A coach can help you adapt a philosophy that can cater to your needs in whatever world you live in.