Because the concept of exercise is a very modern and unnatural thing for humans. We've been moving all day to make a living for most of our history, only when w

Because the concept of exercise is a very modern and unnatural thing for humans. We've been moving all day to make a living for most of our history, only when we switched to sedentary desk jobs did we discover the need to do exercise to maintain our health, but that's like the past 50+ years compared to 50K year history of being hunter gatherers. It doesn't take a prestigious scientist to connect these dots.