If you yawn during exercise – does that mean you’re not working out hard enough? Nope. It’s completely normal. According to neuroscientist Dr. Andrew Newberg, we tend to yawn during our workouts simply because our brain’s trying to cool down. That’s because our head heats up when we exercise, causing our brain to gradually become less efficient. But yawning brings in extra oxygen, lowering brain temperature and boosting our energy. And that helps us exercise longer and more efficiently.