I'm not finding the runs too taxing on my heart & lungs but my legs are getting sore. I do some stretching after each run. I stretch 4 muscles. Quads and hamstrings, calves & and the ones down the front of my shins. However since W2 R3 I've been hobbling a little during the day time. I won't stop the runs unless it gets unbearable but I also don't want to develop an injury that will stop my progress. Any suggestions ?