Stress
Let's see. Insane work schedule? Check. Cross-country travel on a moment's notice? Also check. Flying 200 MPH toward a tree-high inferno? Check check double check. It's probably safe to say that an air tanker pilot's job can get pretty stressful. When you're called out to a fire scene, the slightest inattention to your work can result in disaster.
You can't put the plane on autopilot while you text base. You can't look at how spectacular the fire is, or count the other firefighting aircraft flying uncomfortably close to yours. You must be one hundred percent focused, constantly observing and adapting to changing conditions, and ready to jump to your Plan B with a few seconds' notice. You do have a Plan B, don't you?
In the back of your mind, you're also aware that your aerial and ground teams might provide the final defense against a fire seemingly bent on consuming homes, farms, businesses...perhaps even lives.
Sometimes, your combined efforts may help to save a home, farm, or maybe an entire neighborhood. In other cases, you might fight for hours only to see a wind-driven wall of flames leap a fire line, consuming everything in the fire's path. You'll have to be prepared for that outcome, too.