When I look at my body and when I study my body, I see irrefutable evidence that God does indeed exist. If I were to believe that I wasn't invented by a supreme intelligent being (God), then I'd have to conclude that human beings just came to be. Nature just put this together by a complex set of coincidences. When I look at nature, I just don't see this happening since nature doesn't do things that precisely.
When you look at what nature accomplishes without any intelligence whatsoever, the results are dismal. The actions of plants are proof of this. They lack any sort of intelligence and their only functions are to grow and to reproduce. Both happen without any precision whatsoever. They spread thousands of seeds and at best, a fraction of a percent of them ever amount to anything. As the beings of the natural world start to progress up the level of intelligence, their creations and actions become more precise, more intricate, and more complex. Finally, nature comes to us, the most intellient of them all. We are capable of making things that no animal or plant could ever hope to replicate. Our ability to make the complex and complicated, the intricate and precise is amazing.
If a study of the human body is done, you would see that our bodies and all of the systems in them are anything but random and crude. It is a remarkable creation. It is so well balanced, so intricate and so complex on levels that we may NEVER understand. Just the digestive system alone is amazing in its own right. Now bear in mind we have a dozen more. Even the construction and the functions of the inndivual cells in all of the systems are wonderfully complex. Could we even build something like DNA? We are the most intelligent beings on earth and we can't do it. So, SOMETHING more intelligent had to make us. Nature can't create something like that on its own. Unintelligent nature never has and never will.
Now, with this in mind, how can you NOT exercise? To not exercise and eat poorly strikes me as intelligent as buying a Bentley and never driving it, allowing the rust to pile on from lack of use. It's too beautifully crafted to allow it to rust away from lack of use. Your body is WAY more impressive than any car. Treat it like it is!