If you’re not exercising, you probably think its because you lack willpower. You believe that this mystical force helps fit people up off the sofa and build up a sweat. Our intention to exercise never comes from willpower. Willpower is just a feeling we have whenever we choose to exercise. Our decision to go to the gym can always be traced back to an earlier cause. For example, I’m drawn to the gym by messages from friends. I’m also pushed by the sight of my skinny arms in the mirror. These sights and sounds drive my behaviour. They are not internal, like willpower, but external cues. Every time I exercise can be traced back to some genetic, social or environmental trigger.