In Return to Life, Joseph Pilates describes the "Internal Shower":
"The exercises (Pilates) have stirred your sluggish circulation into action have begun to discharge through the bloodstream the accumulation of fatigue-products created by muscular and mental activities. Your brain clears and your will power functions."
"These exercises induce the heart to pump strong and steadily. As a result, the bloodstream carries and discharges from your system more of the accumulated debris caused by fatigue. Contrology exercises (now called Pilates) drive pure, fresh blood to every muscle fiber of our bodies, particularly to the very important capillaries which ordinarily are rarely ever fully stimulated once we reach adulthood....The result result is that the organs of the body, including important sweat glands, receive the benefit of clean fresh blood carried to them by this rejuvenated bloodstream."
Look for this glow in your clients it's a great sign of knowing that they are connecting properly to their breath and movement.
Be sure to "internal shower" your body daily.