Is this January?

Today the thermometer rose to 76 degrees. I'm loving Texas winters. I ran 6 miles and felt pretty good, even though I was a little worried about my knees at first. On Sunday we went to an indoor ropes course/activity center and played some archery tag, gaga ball, and of course the ropes. My knees felt horrible that evening, probably because of the gaga ball but also because I dropped to my knee at various times on the thinly padded concrete. I iced both knees and felt better in the morning, when I realized I had a bruise on my right knee. Fortunately yesterday was not one of my running days, and I waited until later today to get out, which I think paid off. At first it felt like things could go bad, but surprisingly the rest of the run went okay. And actually the only worries I had toward the end concerned my right ankle, which felt like it was going to buckle a couple of times but held up all right. Is this what it feels like to get old? If so I better keep running.