Definitely rest when you need it. It is amazing. I Ride 8 to 12 miles on my normal days. Once a week I go longer, typically, 16 to 18 miles. After the long day, Ill take a rest day. On that day, I will work abs, and do push-ups, but I save my legs. The day after the rest, you feel so much stronger. Im gradually increasing my distance on both my short and long days.