In this paper we discuss the design process and results from a design exploration on the use of thermal stimuli in body awareness exercises. A user-study was performed on an interactive prototype in the form of an interactive heat mat. The paper brings forth an alternative understanding of heat as a design material that extends the common understanding of thermal stimuli in HCI as a communication modality to instead bring the aesthetic and experiential properties to the fore. Findings account for felt body experiences of thermal stimuli and a number of design qualities related to heat as a design material are formulated, pointing to experiential qualities concerning the felt body, subjectivity and subtleness as well as material qualities concerning materiality, inertia and heat transfer.