Trying to get back into it

Activity: Run
Distance: 4 miles
Time: 38 minutes

Then we took the dog on a walk to get lunch. 2 miles round trip. I had tired legs yesterday. During the marathon training I read and article about injurys and how long you could be "out" with an injury without losing your fitness level. The article said 2 weeks. I disagree with this. I ran a marthon 3 weeks ago and yesterday had tired legs, worse than most long runs, after 4 miles of running and 2 miles of walking. I've got work to do.