It may be tempting to work out for hours every day to reach your goal as fast as possible, but it is not advisable. You need rest days no matter how strong and dedicated you are. If you neglect this part, you may break down sooner or later. Other reasons for resting include:
Preventing CNS fatigue and injury
Whenever you go to the gym to work out, you create microscopic muscular tears. It does not matter if you had a HIIT session or a weight training session. This usually allows the body to adapt, making you stronger. It is not a problem but becomes one when you overdo your training without resting adequately. The micro injuries could become injuries that are more serious and may even prevent you from training.
Boosting morale needed to exercise
It is normal to feel excited when you start a fitness regimen, but consistency is key. Most people lose the motivation to continue in the same spirit over time. This is why you need to take a day off to rest after serious training. You also need enough sleep during this period. This helps ensure that you do not overstrain your muscles.
Working out 3 to 5 times a week is ideal. You can rest for two days or more, perhaps over the weekend.