In this brief, a new optimal control method based on the energy equation of the controlled system is presented. The method proposed here defines a criteria function as the combination of the energy flow equation and the control-performance function, unlike the way the classical optimal control theory using it to define the performance measures. In this approach, the ideal characteristics of a physical system to be controlled are obtained by extremizing the criteria function. The optimal control law is attained by taking the inverse of the ideal characteristics function. The control law and the equations of motion constitute a closed loop to achieve the control process by using a "self-solving characteristic" of a closed-loop system. The method has been illustrated in the examples of an automobile with tires having complex dissipation and an underactuated underwater vehicle with a criteria function given in a complex form.