Difficult people defy logic. Some are blissfully unaware of the negative impact that they have on those around them, and others seem to derive satisfaction from creating chaos and pushing other people's buttons. Either way, they create unnecessary complexity, strife, and worst of all stress.
Studies have long shown that stress can have a lasting, negative impact on the brain. Exposure to even a few days of stress compromises the effectiveness of neurons in the hippocampus—an important brain area responsible for reasoning and memory. Weeks of stress cause reversible damage to neuronal dendrites (the small "arms" that brain cells use to communicate with each other), and months of stress can permanently destroy neurons. Stress is a formidable threat to your success—when stress gets out of control, your brain and your performance suffer.
Most sources of stress at work are easy to identify. If your non-profit is working to land a grant that your organization needs to function, you're bound to feel stress and likely know how to manage it. It's the unexpected sources of stress that take you by surprise and harm you the most.