An exerciser includes an exercising mechanism for being operated by a user who may spend and consume an energy to operate the exercising mechanism, an electric generating device coupled to the exercising mechanism for being actuated by the exercising mechanism to generate an electric energy, a converter coupled to the electric generating device for receiving and converting the electric energy into an alternate current, an electric energy reservoir coupled to the converter for receiving the alternate current generated by the converter, and a control circuit for the exerciser may be coupled to the converter for being energized with the alternate current generated by the converter.