In qi gong, adding oil is also talked about, in the sense that a lamp cannot be lit without a sufficient supply of energy - in this case coming from oil. Our human energy is finite, too, unless we learn how to multiply and store our life force energy. It really is possible, and that is what fuels me to get up early in the morning to do the practices, and that knowing is what will fuel me to get off the computer now to go and finish my exercises!
jiāyóu!