What’s so important about body and breath awareness?

“I would rather be ashes than dust! I would rather that my spark should burn out in a brilliant blaze than it should be stifled by dry rot. I would rather be a superb meteor, every atom of me in magnificent glow, than a sleepy and permanent planet. The proper function of man/woman is to live, not to exist. I shall not waste my days in trying to prolong them. I shall use my time.”