In-field kits and systems for self-directed therapeutic pulley-based muscle rehabilitation methods. The in-field kit and system comprises ring-shaped fasteners that can be removably coupled to preselected locations on a stationary structure, such as a chain link fence. Pulleys are coupled to the ring-shaped fasteners and an inelastic tether spans the pulleys. The tether has a proximal end portion to which a handle is coupled and a distal end portion to which a weight is coupled. The weight and pulleys provide resistance when a person uses the handle to perform any one of a multiplicity of exercise routines. Use of the invention obviates a need to have a physical therapist present at all times during rehabilitation of an injured user because the invention is a pulley-based system usable at home or at an athletic field.