High-intensity exercise is obviously good, but beware of the trap of doing just high intensity exercise and doing it too frequently - the body does not handle that amount of stress particularly well, and it will be counterproductive to your health.

Low intensity exercise that holds your aerobic base is vital as well - and for a well-rounded exercise week, it should constitute the majority of your exercise time.

That is not to say that you should neglect higher intensities, it's just that you cannot do them as often due to the disproportionate amount of fatigue they generate.