Parts I didn't know I had

I'm aware of the tendons behind my knees. For most of my life I was blissfully unaware of the apparatus that houses me. It just worked. Leaving me free to play. Running around and jumping and kicking balls was all possible without warm ups or cool downs. Nothing needed stretching. It just worked. Faithfully and without complaint or obvious need of maintenance or practical attention. But now I'm aware of the tendons behind my knees. The joints in my spine. The nerve signals that carry alarms from angry parts of my body to my brain. All of these functionaries are shouting out that they've had enough. No longer will they subordinate their needs to serve me. They now demand that I take an active role in keeping everything in good order. Keeping fit. That's running around with a purpose. Activity for function not for pleasure. Where's the pleasure in running against a conveyer belt heading nowhere? Riding a stationary bike to get your condition somewhere while you remain in the same place. Serving the machine. If I don't, they warn me, things will only get worse. Work to rule has already kicked in. If I sit for too long my knees cave under me when I attempt to stand. As I rise up to my full height my nerves attack my brain sending it dizzy, just standing up. The rebellion has begun. I am aware of the tendons behind my knees.