A friend and colleague of mine asked me the other day what the best exercises would be to improve posture. She was looking to counteract the sort of hunched forward posture that so many of us experience as a result of sitting in chairs and staring at computer screens all day. My immediate response was to suggest anything that would strengthen the back of the body, i.e. the 'posterior chain' that so many training gurus seem to speak about these days. That is, I told her to do pull-ups, rows, deadlifts, supermans, back extensions, etc., anything that pulls the body backwards and strengthens the muscles to resist that forward, hunched posture.
On reflection, I realized that I recommended pull-ups first on the list. I don't think that it was accidental. To me the pull-up (chin-up too, don't get me wrong) is the perfect exercise. If I was forced to only do one exercise for the rest of my life, it would be the pull-up. My reasons are both pragmatic and metaphysical.
Besides what's been mentioned about posture, the pragmatic reasons are as follows: They can be done anywhere with no equipment. Do you have a body? Great! You can do a pull-up. It might be an assisted one at first. You may need to jump a bit and work on negatives before you can do the real mccoy. You don't need equipment or a gym. You can build your creativity and resourcefulness by finding places in your natural or built environment that allow you to pull your body upward against gravity. Could be a tree branch, could be a bar of scaffolding on your way to work, could be the underside of the stairwell in your office building, could be the monkey bars at your kids' playground. No other exercise is as adaptable or scalable. It CANNOT be outgrown. When I was younger I struggled to do 3 or 4 regular bodyweight pull-ups. Now I do them with 110 lbs hanging from a weight belt. Nobody in the world is so strong that they can't find a more challenging variation to elicit further growth. I'd also argue that no exercise give you a bigger bang for your buck in terms of both usable upper body strength and aesthetic development. Want the illusion of wider shoulders and a smaller waist? Do pull-ups. Want to be able to save your ass from a burning building? Do pull-ups.
Now for the airy fairy philosophical subtext. The pull-up is not just an exercise, it's a powerful metaphor. It's pulling yourself up by your own motherfucking bootstraps. It's resisting the suck of gravity that drags our immortal souls down to the wretched earth. It's telling inertia and complacency to go suck it. It's rising above all of our self-imposed limitations. It's saying that no one but me is responsible for my own success and happiness. It's saying that not even the gravitational force of a planet can resist my willpower and the strength of my sinews. It's showing yourself that no matter how tough things get, no matter how senseless things seem, no matter how much weight and shit and pain gets piled on you - there's nothing in the world that can keep you down.