As every investor knows, uncertainty is the worst possible thing for a budget. And we live in an age of uncertainty: economic instability, climate change, polarizing politics, school shootings, social media, COVID. The world is full of uncertainty, perfectly designed to create a deficit or even bankrupt a human body budget. And you experience this deficit in your body budget as mood. You can think of your mood as a barometer of your body budget. Your brain is always regulating your body; your body is always sending sensory signals back to your brain, and your brain makes these available to itself as simple feelings we call mood. Mood is not emotion; it is a part of consciousness: feeling pleasant, feeling unpleasant, comfortable, uncomfortable, worked-up, tranquil, or whatever else you feel. And when you're living in an age of uncertainty that is creating a body budgeting deficit, you feel it as distress, fatigue, and even exhaustion. You can also feel really worked up at times as your brain attempts to learn in the moment so it can do a better job predicting next time.