I did (attempted) run 1 of week 4 yesterday. My goodness me, it was hard, it was a massive step from Week 3 in my opinion and i'm not sure I was ready for it. I kind of did, I had to walk for a few seconds in both of the five minute runs. I found it very hard. My calves keep knotting/tightening after a few minutes, it really hurts. I have been advised to stretch before as well as after. Not looking forward to tomorrow's run, its forecast to rain as well. Moan over!