A very thin cold and/or heat therapy gel pack with a thickness of approximately 5 mm is designed to conform to the complex contours of a human or animal body through the strategic placement of seams (referred to herein as voids) that allow the gel packs to bend and conform in anatomically correct places to a particular body part. The gel packs may attach to the user via hook and loop closures, buckle closures, strap closures, and adhesive closures. For cold therapy, the gel packs may attach to the user via a pressure sensitive medical adhesive, such as medical tape. Where single-use gel packs are necessary for wound healing, a sterile dressing pad may be embedded in the gel packs. The voids as described herein may also be used on disposable therapy packs that do not contain a gel, such as instant cold therapy packs and instant dry heat packs.