When it comes to building muscle, it’s the time you spend outside the gym when the magic actually happens. When you work out, you create micro-tears in your muscle fibers. Later, your body rebuilds those damaged muscle fibers stronger than before. Your body needs days off to repair, recover, and rest. Without them, you miss out on important muscle synthesis and risk over-training if you work out frequently. This is where active recovery days, along with quality sleep, come in. On active recovery days, go for a walk or do some gentle stretching.