An apparatus and method for creating axial movement of an inner sliding sleeve member on a tool in a downhole environment. The apparatus has keys which mate in a profile on the inner sliding sleeve member, the keys being held in a carrier on a sleeve around an inner mandrel. The inner mandrel includes stops and a lip which can be slid over the keys to retract them for release from the inner sliding sleeve member. By picking up and shifting down the mandrel relative to the sleeve, the apparatus is cycled to jar up, jar down and release. An exercise tool to release a stuck flow tube of a subsurface safety valve is described.