Abstract: An exercise mat assembly comprising an extension pad and a mat body is disclosed. Each comprises a flexible cover, preferably plastic, with flexible padding inside the cover. The mat body is foldable along its transverse axis into two segments. One of these segments has a pocket for storing the extension pad as well as other items such as shoes, containers, and towels. A loop strap sewn to the pocket segment of the mat body at the mid-point of its longitudinal edge thereof, encircles the extension pad loosely enough so that the extension pad may be inserted and removed from the pocket, but tightly enough to hold the extension pad in the appropriate relationship with the mat body during exercise. The extension pad may also be removed from the loop strap and used in spaced relationship with the mat body, thereby allowing the flexibility to adjust the configuration of the extension pad and mat body to conform to differing exercise heeds.