What's that strange smell?

It's 26 degrees outside. I've just walked 8 and a half miles wearing a t-shirt, long-sleeved navy blue fleece, and fleecy track suit bottoms. I appear to have suffered no ill effects other than the beginnings of a blister on one heel. This is good, but I am slightly apprehensive that now I have sat down to type this my body will refuse to get up again...