So Wednesday and Thursday I was feeling particularly tired. Not tired physically just tired sleepy.  Don't know why--I've been getting my usual amount of sleep but maybe I've just been overdoing it and also....I am getting old!  Even so, I was off work Friday and feeling fine so I went ahead with my plan to bump up by distance a bit to 12 miles.  So I set out with plans to do my 6.2 mile loop twice (minus .4 overlap from my own street makes it an even 12).  All was going well until about 8.5 miles when my knee started to hurt pretty badly.  Ended up cutting it short at 11 miles, walking the last 1.  This was odd as I've done 10 many times in the past without pain so we'll give it a rest for a few days then see what's up.  By "rest" I mean I won't do more than 6.2 in a single day.  Seriously, I won't push it as we've got the Cheshire Half Marathon coming up the end of April and I want to be tip-top.