I also liked "muscle confusion". That always worked well for me.
  My first learning was weird though: I was about 12 yrs old and a
  Boy Scout. In the back of a Boys' Life magazine (the magazine
  for Boy Scouting) was an ad for "Charles Atlas". I scraped up my
  change, got a small job after school. Once a month I got a 12
  page photocopy full of exercises, "you can do it advice" about
  something he called "vim and vigor" dated from back in the
  1930s, showing a old-school strong guy in his underpants (if I
  was lucky) doing these exercises where you pitted your muscles
  against each other. No weights, maybe use a chair.

  Anyway, the stuff worked*smile emoticon*By the time I was
  allowed to lift weights in school, I was already ahead of the
  others*smile emoticon