Originally Posted by
terrymorse
To gain fitness, you have two knobs to turn: intensity and volume. I tend to turn the volume knob farther than the intensity knob, but then I have all the time in the world to ride.
This is most of what you need to know.
Sometimes the knobs are interconnected so when you turn up one the other has to decrease a little.
The observable effects are slow, so if you're constantly twiddling the knobs you often can't figure out which does what. Turn the knobs slowly.