Your body clearly benefits from a daily moderate level of exercising. Does your brain care?
Yes, your brain does pay attention to whether you are contracting your muscles, just not always in the ways, or for the reasons, that you might think.
In contrast to your body, your brain benefits most when you perform activities that it evolved to perform—to move around your environment with purpose; movement for diversion or sport is a waste of valuable energy. Your brain benefits when the movement addresses its unique evolutionary priorities related to survival and procreation. Your brain does reward you for moving to explore your environment as much as possible so that you can discover the two most important things out there: food and sex.
Personal survival and the continuation of the species are what brains evolved to achieve. In return for finding food and sex, your brain rewards you, very briefly, with euphoria.
Moderate exercise adapts your tissues to the consequences of the increased oxidative metabolism required to support movement, while too much exercise, particularly over time, pushes metabolic demands to the point that your brain’s innate protective systems are overwhelmed; the increasing levels of toxic chemicals, called reactive oxygen species (ROS), that lead to cellular injury and accelerated aging.