Using the equation of motion expression in a curved space proper time is a useful method to explain the relation between the curvature of space-time and the potential of any field obtained. Taking into account the expression for the Hamiltonian density, the effect of fields, as well as the effect of motion, on the mass, and, their effect on energy is found. The new expression of energy reduced to the ordinary Newton's energy expression. It also explains the gravitational red shift.