When you run to stay in shape you often only keep track of your mileages, since numbers are fun and your speed. But I should really also mention how often I just rest from running. Life is all about balance. So I try to go running when I feel like running. If I don't feel like it I try to rest that day.
After running 10 miles on Sat, and then racing in a speedy 5k on the next day, I did nothing on Monday (except garden a lot). My back was sore and my legs fatigued on Tuesday and that along with a rainstorm led my training team to cycle indoors instead of run. I was relieved to not push my legs with another run. Today, Wednesday, I might still rest from running as I feel fatigued.
I'll save up my energy for a run on Thursday morning when Nate can help watch the kids.
I plan to keep running my 20 miles a week...but that includes days of rest which are relaxing and allow my legs to recover their vigor.