Maria has an unusually strong constitution, which produces the highest quality blood and plasma available for transfusions. She manages to stay healthy while donating blood at the hospital two or three times a week. For each blood donation, the hospital pays Maria $175. Maria drives 40 miles round-trip to the hospital to make her donation. Moreover, she spends about $135 every month for vitamins and other pills prescribed by her physician to ensure that her general health and blood quality do not degenerate in light of her frequent donations. Last year, Maria quit all of her part-time jobs and now survives financially solely by these blood donations. Specify the tax consequences of this regular activity.