I decided that since I exercised today, I plan on hurting later on.
What kind of exercise did you do? 
I rode a stationary bike for 15 minutes, about 1 and 1/2 miles. Bad knee means biking and swimming are the safest exercises for me.
Interesting that the biking doesn't hurt your knee! Good for you, I tried to start a treadmill habit once, but after my first 9-minute workout,
my downstairs neighbor knocked on my door to tell me that her overhead light fixture was trembling! That was the end of that!
