I'm in week three at the moment, just about to complete w3r3.
I ran w3r1 outdoors and reeeeally really struggled with it, but then did w3r2 on a treadmill and didn't find it too bad at all... I'm not sure if its because it was warm weather and the road was kind of hilly when I ran outside, but I didn't think it would make such a big difference!
Am I cheating myself by running on a treadmill and making it easier than it should be? Where do other people run?