Abstract: A ball hitting training device has a ball hitting implement such as a baseball bat or golf club, a shoulder harness or anchoring device for wearing on a player's leading shoulder when taking a swing with the hitting implement, and an elongate tether of flexible, non-extensible material having a first end secured to the shoulder harness and a second end secured to a location at or adjacent the ball striking end of the hitting implement. By maintaining the tether taut during a practice swing, the player can establish a so-called magic triangle between the hands, the ball hitting end of the hitting implement, and the leading shoulder, and can maintain this triangular relationship throughout the swing.