I have flown through c25k until wk6d2. Day 2 was hard enough but I finished it. The following day I had a sore knee (I have a dodgy knee anyway) and took a week off to recover. Since then I repeated week 6 day 1 and 2 several times to ease myself back in. I have attempted w6d3 twice now but I keep having to stop now and again however it is mostly running. I feel that w6 is holding me back - how can I overcome this?