"There is no exact measure for it, but yes, as we learn our magic we learn how to feel out our levels of mana. Mana and your body's normal energy are separate, but they still affect one another. If you are suddenly cut off from accessing your magic the mage can easily become disorientated or a time, or if you use too much mana you can become magically fatigued and thus tired, or headaches might occur. If your body is overburdened such as being sick you might not be able to cast well."

He smiles some, rubbing the back of his head again, knowing he's throwing a lot at her.