Give yourself unlimited health, stamina and food. Run around everywhere without needing to stop, never starve and never die.
Prevent your health from lowering. This will prevent you from taking damage.
Prevent your stamina from lowering. This allows you to sprint, swim, fight in combat and more without ever needing to stop.
Prevent your food from lowering. This means you can't starve and no longer need to maintain your food metre. The food metre is the green bar in the bottom left hand corner.