Honey, you better not be overworking yourself out there.
Are you kidding? I'm fine! My cardiovascular system is keeping everything going!
See 'dear' I told you I was going to be fine. The cardiovascular system is so awesome. It delivers all the nutrients my organs need to outrun hunters all day. It even helps get rid of cell waste and move the cells that fight any foreign bodies like bullets.
Well how about you get some food and water to replenish those cells. You can't outrun anybody if your cardiovascular system doesn't have any fuel. You need the break so you don't get too exhausted or fatigued anyways.