A healthy mind lives in a healthy body.

There are a couple kinds of happiness, viz. Health, wealth, mental, emotional, etc. Health is considered more valuable amongst them for a simple reason as the other are secondary elements of happiness. If we are free from the worries of health then we can concentrate on our tasks. Consider a simple example, your productivity goes down drastically if you have a cold or a headache correct? So the absence of any ailments would help us achieve better productivity and hence satisfy the secondary elements of happiness. That's why we should look after our body and to take care of our body we need to understand the body better. Lets try to make the body more robust after learning about the body.