Self-contained disposable single-use heat generating apparatuses and methods for providing heat are disclosed. One exemplary apparatus includes a heat generating pack having a first bag layer defined by a first surface area bonded to a second bag layer defined by a second surface area and creating multiple pouches therebetween. A heat generating agent is disposed within the pouches and adapted to consume air at a predetermined consumption rate in an exothermic reaction. At least a portion of one of the first surface area and the second surface area comprises an air permeable surface area having a predetermined airflow rate such that the heat generating agent remains substantially evenly distributed within the pouches.
