[Mark McLeod]

You need an interlock, something along the pseudo-code lines of:

boolean belt = false;
boolean toggle = true;
 
if (toggle && Button) {  // Only execute once per Button push
  toggle = false;  // Prevents this section of code from being called again until the Button is released and re-pressed
  if (belt) {  // Decide which way to set the motor this time through (or use this as a motor value instead)
    belt= false;
    conveyorMotor.set(1);
  } else {
    belt= true;
    conveyorMotor.set(0);
  }
} else if(Button == FALSE) { 
    toggle = true; // Button has been released, so this allows a re-press to activate the code above.
}