If you’re a coach, you probably don’t ask your clients about diet, exercise, or sleep habits. But low affect, or feeling down, can have a physical cause. That’s because the purpose of the brain is not to make us happy, or make rational decisions, but to ensure that we grow, survive and reproduce. This is why we need to look at the brain and body as a whole. And the brain works to keep your mind-body system in balance, so you can grow, survive, and reproduce.