The average adult body has around 100 trillion cells. New cells are replicated daily from existing ones to replace the dying or damaged cells. In fact, every seven years, nearly all of your cells will have been replaced, which means your current self will share almost no physical matter with your future self. This fact underscores the importance of keeping your cells healthy now, to keep future generations of cells healthy.age adult body has around 100 trillion cells. New cells are replicated daily from existing ones to replace the dying or damaged cells. In fact, every seven years, nearly all of your cells will have been replaced, which means your current self will share almost no physical matter with your future self. This fact underscores the importance of keeping your cells healthy now, to keep future generations of cells healthy.