Ancient Indian saints expressed that the body is the temple and the heart is the light of life. When the body is not kept clean and clear of ailments the heart doesn't go on. I always add to this by saying the body is the temple, the heart is the light, and the mind is the guide. When one can follow with the intellect that is provided by the mind and take care of the body and heart, one can reach the heights of joy and rewards that could come along with health. In other words, a healthy body leads to a healthy heart which leads to a tranquil mind which in turn leads to a healthy and happy long life. One doesn't work with out the other. When the body is neglected it weakens and cannot protect the heart and when the heart is not working well the mind goes through upheavals. It is a reciprocal theory.
Everything is interconnected. I came to realize this a little too late in life. I abused my body very much. I ate everything that was in sight, never exercised, never followed the rules of nature to discipline myself by going to bed early, and focusing on some spiritual guidance. Eventually, I ended up with various ailments and started taking care of myself. Sometimes it feels like it's too late but most of the times it feels like it isn't. Of all the three components of life the heart is the center point for survival and needs to be paid special attention to.
A human heart pumps five to six gallons of blood through the entire body each minute. It beats 100,000 times per day to circulate the blood. It is the power house of the body that is constantly working to keep one alive. And when it stops, life stops. Major functions of the heart include taking de-oxygenated blood through the veins from all parts of the body, adding oxygen from the lungs and then pumping it through the arteries to different parts. The heart has its own supply of blood and oxygen through coronary arteries and veins to keep its muscle healthy and strong.
When the heart vessels carrying blood supply to the heart muscle are corrupted with cholesterol, fat, calcium deposits, and plaques they narrow down in a condition called atherosceloris.