Should we all be hitting the gym three times a week, doing yoga, HIIT training or simply getting in our 10,000 step per day? How much does physical activity affect your bodyweight and is this affected by your genes? Does carrying too much weight make you less active? Does how we measure physical activity influence how much we need to do? Should we worry about sitting too much? And if you are strong and fit can you get away with being inactive?  With new exercise fads cropping up, seemingly, by the day, how are we supposed to know what to do to stay healthy? In this interactive lecture, Professor Jason Gill reveals what science can really tell us about how much we need to move to maximise our chances of a healthy life, followed by a Q&A.