Listening to music while you exercise helps give you the enthusiasm to keep up the intensity for the full 20 minutes. Download appropriate tunes on your iPod: choose a lightweight version with an armband or belt clip so you donít have to carry it. Alternatively, make yourself an exercise tape or CD. Choose beats you can move in sync with studies suggest this makes exercisers train at higher intensity and vary the tempo for warming up, high impact work, cooling down and chilling out. During the aerobic section, take the tempo up and down rather than starting slow and getting faster.