For in everything that we do the body is useful; and in all uses of the body it is of great importance to be in as high a state of physical fitness as possible.
A holistic view of fitness would have to include not only the muscles and heart and bones like most training protocols do, but also the brain.
We have to view the body as a synergistic system, and that includes the brain. Everything that our muscles do is tied up with our minds and nervous system.
So if you really want to be the best version of yourself physically, then you need to train your mind. Luckily for us there is no better time in history to train our whole bodies. Books are everywhere, paper and online. Articles abound online, thousands of videos and audio format information exist.
Push your brain out of its comfort zone, the same as you would do for your muscles. This will not only make you a more intelligent human, but it will help you to master your emotions, one of the greatest boons of humanity and also our greatest enemy. Uncontrolled emotions are one of the main reasons we do dumb shit over and over again, and should be trained like any skill, as young as possible.
Once all that’s done, get your ass off the couch and get outside, get some fresh air, walk a lot, run sometimes, lift some heavy stuff and have some fun.