I'm getting old or something

Hmm, having an interesting issue in the last few days. I have been running like a little maniac (not quickly mind you, but still running), and my body is definately paying for it. My knee is sore and so is my previously injured ankle. However, it pretty much goes away once I am warmed up and running. I don't really want to stop running, it has always worked for me and I feel better when I am getting in at least a 30 minute run everyday (right now I am running for 40 minutes). However, I don't want to mess up my knee either and cause real damage. So, this is my thought, which may be silly in the extreme. I am going to run tomorrow and Friday and take Saturday off and reassess where I am with everything. It is possible that this is just my body protesting two hours of cardio a day and 40 minutes of running (especially since I stopped running back in January). Therefore, a day off would make a real valid difference and I can see what is up with the aches and pains. Alternatively, nothing will change and I will have to reevaluate. I would like to get back to running at about 6 mph (rather than 5 mph) and running for an hour at a time, but I am not going to chance it until my knee really begins to feel better. I am hoping this is all muscle soreness and it will go away. Oh, and food is excellent (see what happens when I am not under stress).