But what constitutes a great body? Everyone has their own personal ideal, but to me every single body is great. I've seen guys missing legs that had an inner, as well as outer, strength few four limbed bipeds possess. Consistently seeking improvement is the key. In other words get some guts. Most people don't have the guts to train hard. Or the guts to eat healthy. Or the guts to take responsibility for their health. The average human being is having a near-life experience.
Nobody has a "bad back", "bad knees", etc. We've just treated ourselves poorly and got back what we gave. Every thought we think, and every thing we do creates chemical reactions within. We create our health moment by moment. Every decision weakens or strengthens. So get some guts. Decide what kind of body you want, then start taking steps toward that. A great body might require a great effort. Or maybe it won't. It could very well be that it is much easier than you think.