Yes, I am an idiot.
Went for a walk (it's not cold out, it's brisk). After heading down to Dyckman and back I veered into Inwood Hill Park and into the wooded portion (via a winding path). I should have turned back as soon as I saw that the path (completely shaded by the thick surrounding trees) was covered with ice and snow. Instead, I wandered in, figuring there was enough snow for me to find my way without having to walk over bare ice. I fell three times before I could make it out again, to where the path was clear. Each time I fell I was down for a few minutes, trying to find the position and the footing which would allow me to right myself without slipping again. When I did finally emerge (covered in dirty snow, my hip, knee and ankle smarting and sore) I hobbled over to the Indian Road Cafe where I ordered a jalapeno-laced hot chocolate wherein to drown my pain and embarrassment. I thereby undid, of course, any possible caloric good the walk might have done me.
Now, home, it's ibuprofen and a comfy chair for me.