What controls the “brain?”

I understand the concept of the primal brain, and that all of our urges stem from the need to stay safe and alive.

My confusion comes from this question: what controls the “brain?” Coaches are always saying you need to control your brain, and pay attention when your brain wants or does or thinks something.

But if the brain is what we are controlling, with what are we controlling it? Does the brain control the brain? Or is it the subconscious, or a higher power?