Calisthenics is an accessible form of physical training, where, like all training methods, optimum results come from good form. Improving form generally requires feedback from someone with greater experience, which can affect training accessibility. This is remedied by existing applications which provide form feedback, however not without issues, as rarely do these applications handle exercise progressions–such is the case with the push-up, a low-equipment calisthenics exercise with many progressions. This study presents the design of Progress-Up: a mobile application to provide real-time form feedback for various push-up progressions as an alternative to traditional coaching. Progress-Up leverages a 2D human pose estimation model and angle-based heuristics to interpret user form, count repetitions, and provide personalized feedback on each repetition. The design is motivated by existing form-feedback techniques and applications, and is analyzed by a discussion of its strengths and weaknesses. A prototype application of the design was developed, and was evaluated to be capable of distinguishing good and poor form, but is inconsistent when in poor environmental conditions. Ultimately, this work aims to contribute to making quality physical training more accessible, regardless of resources or experience.