Once you can "see" what is happening inside the body in an immediate and continuous way, it is possible to control it. So far, nothing that can be observed in this way is impossible to control, from a single motor neuron (the nerve cell that controls a muscle fiber), to processes such as circulation or secretion of stomach acids.

 There is nothing mysterious about this. Everything that we learn is learned through feedback, from the time that we first find our mouth with our hand as a baby. Biofeedback simply involves applying these same learning processes that we use in putting on makeup or driving a car to inside-the-body events. It is "mind over matter," but in that it is no different than our filling a glass with water: that also is mind over matter.