Your body reacts to Stimulus not Rest. It recovers, builds and maintains during Rest BUT without stimulus it can do nothing but simply maintain (it can't even do that - if training is left for too long). Training is the most important factor when it comes to changing your body, Nutrition is the 2nd most important and Rest and Recovery 3rd along with Hormone Secretion levels, Metabolism Speed and Insulin Sensitivity. We do need rest, but what can we avoid so we don't rest too much?
1. Sleeping Too Much
We need a high quality sleep - not necessarily a lot of sleep. High quality sleep allows proper rest and repair and should be kept within night time hours, not day time. If you are napping during the day, chances are that you are not getting high quality sleep and you must improve your sleeping window (go to bed earlier and wake up earlier). This allows for hormones to be secreted at the right times. A lazy bodybuilder is not a good bodybuilder any more, keep awake and move a lot to increase metabolism, fat burn and nutrient delivery.
2. Too Many Off Days
Once you know about rest and recovery, more emphasis is placed on it - but sometimes too much. Always remember your body will react to stimulus by changing, no stimulus = no change. Going more than 3 days without training Intensely will not challenge your nervous system and it may slow down metabolism. How is your body meant to change if you are not training enough? Fit in 3-4 days of Intense weight training days per week (depending on level) and 1-2 cardio sessions per week (if inactive during the day) to keep your metabolism and goals moving forward.
3. Too Long Rest Periods
This is a fast track to an easy workout. This is so easy to do that it's worth repeating a thousand times; Very long rest periods will not change your body quickly. This is true in 3 ways; it reduces the amount of Volume + Density you can perform during the workout period, it prolongs your overall workout time past an optimal window, and it vastly reduces training Intensity - which is a fundamental law of progress in fitness and bodybuilding. So many people have a default switch on in their brain which is telling them to make their workout easier, when the opposite is the only way to give them results they desire. Aim for 30-45 secs rest between sets for upper body + calves, 60-90 secs for legs.
4. Not Training During A Holiday
There's a movement being spoken about by fitness coaches/ trainers that claims taking 7 days off training every now and then is vital for recovery of muscles and the nervous system, which has a whole list of benefits for your potential progress. All that can be said about this is to bring you back to the principle of this article. Your body reacts to stimulus, not rest; no stimulus = no change. Any program that requires 7 days rest every few weeks is probably the wrong program. Your holiday is the best time to actually train your hardest, as you should be completely stress free and have ample time to re-cooperate. The early nights, good food, fun with family and friends is the perfect opportunity for progress you could possibly hope for. Taking 7 days off training would send the avid gym goer crazy and just prolong results. Train hard and relax. Instead of taking too much time off, it's recommended to get a deep tissue massage once a month to help with stiffness and fatigue.
5. Nurse An Injury By Not Training
A doctor will tell you to rest an injury, and in some cases you definitely should. However, if you can work around an injury without causing it too much pain then you absolutely must do it. Prolonged elevated heart rate will deliver nutrients at a faster rate towards damaged areas in need of repair and chemicals produced from training help the body adapt and recover as a whole. Many injuries are recurring aches and pains, most of the time the pain is located in the muscle and is caused through muscular imbalance. Big aggressors are either posture related or over-trained areas causing repetitive strain injuries, or dominating weaker antagonist muscles, e.g. Tight over-trained chest muscles pulling at back muscles, resulting in hunching and possible neck and back pain. Take a full body approach and perform equal volume on all muscle groups to avoid this, and be vigilant about posture at all times.