Change often involves loss, so change can be a risky experience.
Years of research show us that the less control a person feels over an aversive stimuli coming at them, the more likely they are to disengage. Complete loss of control over a sustained period of time can actually lead to depression. It then follows that giving the person a level of control over the situation reduce the stress - and perhaps restore the disengagement.
There are estimates that we daily walked for 10 - 20 kilometers for hundreds of thousands of years. The world's best problem solving machinery grew up under conditions of consistent, strenuous physical activity. It makes sense that when we don't recreate the environments in which the organ was forged, we get a loss of function. And that when we do restore those environments, we get that function back. The effects of aerobic exercise on executive function skills is a powerful empirical example of this idea.
The brain doesn't care about change. As the world's most sophisticated survival organ, the brain cares about loss.
