"Membership in my gym is only by invitation after an initial evaluation and interview. You can be 92 years old, or you can be an Olympic lifter. Our sole criterion is that you must be dedicated about improving yourself, because our goal will be to make you physically quite uncomfortable, and more dissatisfied with yourself than you were when you arrived. If you are fat or weak, we will not tell you that you are fine the way you are, because it would not be true."
Paraphrase from a Mark Rippetoe interview