Because HIIT workouts are more exhaustive then steady state endurance workouts, a longer recovery period is often needed. Try starting with one HIIT training workout a week, with your other workouts being steady state workouts. As you feel ready for more of a challenge, add a second one.
Once again, HIIT is not for someone just starting to get into shape. Take the time to get to know your body. Listen to what it tells you and go slow at first. If you feel you are ready to take your fitness to the next level however, then by all means, give HIIT a shot!
