Weak in the Knees

Today I made it out for 3x1200 intervals.  The day was lovely, but my knees are still feeling sore - so i'm going to take the next 3 or 4 days off - or maybe the rest of the week.  Not the best - but I feel they are at the point of overuse and need a break.  Wish they could last one more week - but such is life...