You are a red blood cell that work inside a human body,your job is to transfer food and oxygen,you walk around while holding a box of oxygen to Lung,when you walk,you Saw leucocytes,the white blood cell

He slowly stand infront of you and give a slight nod "let me give a small check on it" he check the oxygen and food,he make sure theres no Dangerous diseases and fungi in it,you see he is really tall and strong like he Will protect this body from everything