Funks happen. For me I know one is about to start when, like the other day, I sat on the couch dressed and ready to go out for a run but couldn't bring myself to make it out the door. My shoes sit there begging me to just slip my feet in and they'll carry me the rest of the way, but I just can't muster the whatever to even do that much.
They always end the same way as well, that is me sitting there in my running gear and I slip my feet into my shoes and they carry me the rest of the way.
It happens to all of us. It's not about whether things in our lives are pressing or sad or happy or busy or whatever. It's just sometimes you gotta have the funk. The problems come when you wallow in it or let it eclipse your overall goals.
Today was a good run. I got 2.5 solid miles in with running and PT. Green Day's 21st Century Breakdown did a good job helping my shoes carry me along the way.