Just got back from my first 28 minute run, and I covered 2.64 miles according to endomondo. Both knees are aching, but so far no sign of the pain in my weak knee.
I'm pretty chuffed that I managed both w7r3 (after a 20 day rest) and w8r1 (after an 8 day rest) first time and I've upped my pace to the point where 5K in 30-ish minutes seems realistic.
For anyone out there resting their knees I can heartily recommend getting the bike out. I've been going out for a brisk 30 minute ride most mornings and I am sure that that has helped increase my stamina and overall fitness whilst not putting any strain on my bad knee (I was advised by my physio that cycling was a good idea "as long as you are not standing on the pedals").
I am now in the revolting (to my former self of only 4 months and 4 stone ago) position of wanting/having to do some exercise every day, be it cycling, swimming or kayaking, although I remain rightly repulsed by any thought of organised competitive or (shudder) "team" sport