Understand the "Gravity" of the situation
At the tender age of 23, Isaac Newton, the greatest scientist of his time created a paradigm shift in human understanding of the physical world, and changed the course of the world as we see it today. It took a genius mind to figure out that an apple falling from a tree toward the earth was caused by an attractive force from another exponentially larger mass, called Earth. By observing the trajectory of Halley's comet, he was further able to prove his theory and get it published in a book called The Principia: Mathematical Principals of Natural Philosophy in 1687. With this book, the world was enlightened to a new universal set of laws to understand our physical state.
Why is Gravity essential?
The takeaway from this is that as residents on Earth, we are and always will be subject to one constant, Gravity. There are numerous studies showing how our bodies are affected by gravity. Long story short, gravity is necessary for our bodies to understand what it needs to do to function normally. You can apply the laws of gravity to every single cell in the human body and it will relate in some way to it's core function. Because of NASA's work, we are now able to understand the effects of not being under the influence of gravity.
Gravity is a force that acts on our bodies. All forces change matter over time. Since we are matter, we are subject to those changes. Eventually, Gravity will also destroy us...much like any other force. Now that's a true dichotomy.
Here's an example:
The discs in our spine are filled with nerve endings that communicate with the spinal cord to give cues to the brain about our position. These receptors get stimulated when pressure is exerted on it. Because the force of gravity pulls the mass of our bodies toward earth, there is more loading on these discs when we are sitting or standing. That sends signals to the brain, allowing it to relay new signals to the spinal cord and muscles to keep us in an upright position so we don't fall. This happens simultaneously. This is a very basic explanation, as there are years of research that can be done of each of these phenomena, and many more that I have not mentioned due to fear of losing your interest.
Why will it kill us?
Over time, our bodies will be unable to keep up with the constant demand of gravity. Imagine that you are asked to wear a backpack for an hour. By the end of it, you will be more than happy to take it off. Now imagine not being able to take it off? Your body will adapt in the best way possible, but eventually it will break down faster. That break down will lead to a shorter life span. This means you will actually die faster if you were never able to take the backpack off. Now imagine that gravity basically does this to your body, but in a less obvious way because you're born into it and never knew any better. The relationship to gravity (your environment) has been embedded into your DNA. Kinda makes you think about the argument about nature vs nurture doesn't it. If you understand this concept, you understand that both play equal roles in your development. The real question here is...if we moved away from the Earth, would we evolve to live without gravity? If so, will that increase or shorten our lives?
What we need to know about Gravity today
While Gravity is essential in creating us and destroying us, what is important is what we do in between those two events. By securing our bodies in the greatest set of circumstances to live in gravity we can harness this great power for our benefit and not for our destruction.
BMI
Body Mass Index: Simple concept. You height and weight will determine how much effect gravity has on your body. The more you weigh and the shorter you are, your body will be heavier on your antigravity supporting structures (bones, muscles, ligaments, myofascia). That means you'll break down faster and have a shorter life span.
Strength
The ultimate anti-gravity support system is your musculoskeletal system. Without it, you are not going to get up and move. Movement is the antidote to inertia. It will literally keep us alive longer. The more the muscles are working, the less likely the negative effects of Earth's gravity. One simple way to get strength to fight against gravity is by working on your posture. This is a basic concept, and it alone will not help.
Coordination
Muscles need to be controlled properly so that your movements can be smooth and rhythmic. These are controlled by a complex set of systems and reflexes designed to help you accomplish the most efficient movement. However, depending on the level of disruption of impairment in this system, your movements will be less than ideal, resulting in damage. Most of the coordination can be improved by focusing and practicing good body mechanics.
Impact
The lesser the impact of our body when it comes in contact with the earth, the less damage we sustain. Seems easy enough. We just need to make sure we don't fall, or jump off high buildings. But the impacts that are small also accumulate damage over time. Take walking for example. Every time the heel touches the floor, your body weight is coming down and causing vibrations to go up and down your entire skeleton. Doesn't seem like much right now, but imagine years of this. Eventually, the knees, hips, spine and many other structures will break down. Simply by softening your landing, you will preserve these joints for many more years and keep your movement system running great. The best way to control this is by practicing a good gait pattern.
Conclusion
Gravity is the constant force that will make us and break us. By understanding how it works, and how our bodies are affected by and respond to it, you will have a better way to navigate life. There is no magic bullet here. It takes concentration and repetition. But once you start this journey, you will see a significant improvement of your life over time. In addition, it will help you to live longer with a higher quality of life.