Related:

• Aerobics instructors do it until it hurts.
• Hackers do it in less space.
• Practice is the best of all instructors. -- Publiliu
• Electrical Engineers do it with less resistance.
• How many aerobics instructors -- does it take to change a light bulb?
  Five. Four to do it in perfect synchrony and one to stand there going "To the left, and to the left, and to the left, and to the left, and take it out, and put it down, and pick it up, and put it in, and to the right, and to the right, and to the right, and to the right....