In mid-November I was away, effectively for two weeks, and on coming home asked on this forum for ideas on how to restart running. runswithdogs suggested Week 4 as a guide, and it worked well - the first time. The second run, a few days later, had a quite different effect and left me with very sore knees. Since then, kneeling or any other action involving bending knees has been painful. After forgetting running for a week or two, I tried a very gentle run, covering only 50 metres or so at a time and then walking, over a period of 20-30 minutes. No improvement and knees were at least as sore as they were before. Finally, I saw my physio and she diagnosed insufficient stretching. My aim when I started C25K was to do a parkrun at Christmas. I've already done three parkruns but there are only a few days to the target and I wonder whether I'll have stretched enough to attempt it. Incidentally, I am also enduring the foam roller torture, as well as the exercises. Foam sounded nice and soft but my roller looks like an HGV tyre and is somewhat harder.