Mark originally started out in the racing community where he enjoyed race management and coaching youth runners. In 2002 he transitioned into the footwear business by opening up On Your Marx Running at the Lowell location. With some success, he then opened the Acton Location.

From there he developed an intricate gait analysis system to ensure individuals' footwear is working for them every step of the way. This is now partnered with the Shoe Lab, where employees perform statistical analysis on shoes and determine different qualities and specs of the shoes so they are able to give proper recommendations.