Maybe it's because you ran 9 miles the day before? I'm sure I'd need rest if I did that. I have found that the more I go running, the less tired my legs seem to become after each run. I haven't gone out since Tuesday though. I had a great 5.2 miles on Tuesday but then I ended up walking something like 7 miles later on. I felt my shins hurting from that the next day but I still couldn't rest. Since Tuesday I've walked a minimum of 6 miles each day, sometimes more! I'm going to try get out tomorrow for a run but this walking distance will continue everyday until atleast Friday next week.