The harder you work, the more you need to recover. In recovering, you allow your muscles to grow. Due to the intense amount of work I've been doing over the past week, in one day of resting, I felt great. The muscles in my legs really felt great. When you take in a lot of protein, during your resting time, your body uses that time and energy to shoot that energy straight into the muscle. Your body can really sense the recovery and with the muscles receiving the energy and growing, you begin to feel that difference.
After I came back, I felt ready to run, but since it was a break, I just took it. Tomorrow, can't wait to go on that long run.