After moderate to intense exercise, do your best to keep moving to ‘cooldown’ – especially when in the heat. Most importantly, this mitigates rapid declines in blood pressure which may lead to dizziness or fainting (syncope). However, after very high-intensity exercise (sprints) and you’re exhausted to the point you don’t feel like you can move any more, at the very least lie down flat to help your body more effectively circulate blood.