Abstract: A weight lifting machine provides an instantaneous variable resistance, which can be adjusted manually during a workout routine or through a program, which has been selected by the user prior the workout routine. The weight lifting machine includes a pair of guides and a stack of weights which are slidably mounted on the guides and movable along the guides from a rest position to an elevated position. The weight lifting machine also includes a selector member and a lift member. Each of the weights includes an opening to receive the selector member. The openings are aligned to define a transverse passage through the stack of weights to allow the selector member to couple to each of the weights in the stack. The selector member includes a plurality of couplers which are adapted to instantaneously couple to and decouple from respective weights of the stack of weights.