After having something pulled in my knee at Week 9 R 1 (maddening!) I thought it wise not to run until it was better. Saw the doctor (himself a marathon runner) who diagnosed I was over-pronating - fortunately no evidence of arthritis - and said to go to the gait analysis place. Armed with a new pair of Asics that cost an inordinate amount, but well worth it, I've been gradually building up to avoid too much stress on the knee. Another doc friend said the only way to protect the knee was to strengthen the muscles with exercise, so lots of quad stretches, hamstring stretches, wall squats etc, and starting with short runs.
A figure of 8 circuit round Albert Park in the old part of Abingdon is almost exactly 1 km, so a half circuit is about 0.5 km so one can build up in easy increments. This was 2 km, at 0715 on a Saturday morning, so feeling very smug and virtuous. Start at the St. Michael's church entrance, go straight across to the Albert statue, circle back left, then across again and circle right. Then repeat. When I'm confident I can do that five times without wrecking my knee then I'll be ready for Park run. Might also be a good venue to do the rest of Week 9. (I'm very slow - that'll be 4 figure of 8 circuits).
It's a lovely part of Abingdon, surrounded by lots of elegant old houses in private roads.