David Phillips teaches through the Titleist Performance Institute, the leading golf fitness and biomechanics education organization that has fundamentally changed how the golf world thinks about the relationship between physical capabilities, movement patterns, and swing mechanics. TPI-certified professionals are trained to evaluate how the body's physical limitations — mobility restrictions, strength imbalances, flexibility deficits — create compensation patterns in the golf swing that no amount of technical instruction can fully correct without also addressing the underlying physical causes. Phillips's work through TPI represents one of the most important developments in modern golf instruction: the recognition that the swing is produced by the body, and that improving the swing sustainably often requires improving the body's capacity to support the movements that better ball-striking requires.