I started my run planning on running 5 miles, but after about 1/3 mile I could tell my right knee was weak. By the time I got to 3/4 mile the knee was feeling sore each time the leg hit the ground. I turned around and walked about 1/4 mile and then jogged the rest of the distance back to my car. By the time I got to the parking lot, the knee was feeling fine. I probably could have kept on running, but I didn't want to take chances with the knee, and I'm glad I aborted.
It was a beautiful but a bit cold day with the temperature in the mid 40s (F) and a 3-4 mph wind. Lots of sun and nice clouds.