Have you ever had an injury? Nevermind I know the answer. Yes. You have. If you've been running for over two years you have. Not because running is 'bad for your knees' or 'gives you arthritis' (who makes that sh** up?) but because it's an intoxicating sport. And we all have weakness, imbalances, stiff muscles, what-have-you. Yet no one has the time to do all the meticulous work to keep our engines running in all their gleaming possible perfection.
But we can't stop running, because we are in love. Until injury hits you like a brick wall (or a semi truck) and lands you on your butt. Wind knocked out. Shocked to watch the running turn it's back on you for days, weeks, months.
Once you've been brick-walled and/or semi-trucked you catch your breath and then you start crawling back. You aqua jog at 5am and see your PT more than your friends, you might even go under the knife and, of course, you your make pleas to the running gods and then ... you're back. Because running isn't puppy love. It's lifelong, through sickness and health kind of love.
Anyway what I'm trying to say is my knee is being a jerk.