Mister W.
As luck would have it, I've been training and trail racing in preparation for this years Manx Mountain Marathon. Its 31 miles of up and down fells.
It did not help that ran a 15 mile fell race two weeks ago when the knee was partly injured (I know, I'm stupid).
..I've never even done a marathon before, so I'm biting off a lot to chew in a few weeks.
One month before the race and the knee problem comes.
Its a delicate balance between maintaining high levels of fitness, whilst also limiting activity such that you dont make the injury worse.
For me running is the hardest thing I do. Swimming and cycling are a poor second and third. So a two hour run would be equivalent to a four hour ride... and I dont have all day to go out on a bike ride.
As per your advice, I normally listen to what my body is telling me. I can live with the odd twinge, but swollen sore joints which are painful to move even in bed are too much.
.. the longest rest I've had in two years running are the past 5 days, with this blinking knee.
Psychologically I just need to chill out a bit, but you know what its like....