1. Don't forget to breathe
    You mean "breathe deeply." It is physiologically impossible to forget to breathe. Don't make me slap you
  2. Activate your glutes
    Do I need an activation code? Should I call tech support?
  3. Engage your core
    We're doing sit ups. Is someone here lifting their upper body from the floor without engaging their core? Rope and pulley perhaps?
  4. Don't let you knees go over your toes.
    I'm no doctor but I'm pretty sure your knees are always over your toes...
    Suggested by   @donnie
  5. Sits bones
    Isn't this just one's ass?
    Suggested by   @gilbaron
  6. Suck in your belly button.
    Suggested by   @girgentiam
  7. Breathe into your side body.
    How?? My lungs are in my chest, not my obliques. I cannot selectively breathe into other areas of my body.
    Suggested by   @talleycook