Stay active by using your body and brain.
“Iron rusts from disuse; stagnant water loses its purity and in cold weather becomes frozen; even so does inaction sap the vigor of the mind.”
So said Leonardo da Vinci in his many notebooks on his observations of nature.
The human body is an efficient machine, which will eliminate what is unused. For instance if you exercise, you build muscles and a better blood circulation. When you stop exercising, the excess muscles, nerves, bones and blood system are cut away as unrequired.
Heart and brain are closely connected, so if there is a problem in one, then the other suffers too. Keeping both brain and body active is important, as it slows the decay in the body and mind. By being inactive in mind and body you are telling your body it is ready to die, so you will age fast and die fast.
Use your brain and body every day by pushing it through a limit. Youth and health are a blessing, and one that is easily destroyed through inactivity and bad habits.