How do you get yourself out of a funk?

I'm not finding much motivation to do anything. I force myself to do my workout classes, because I pay for those, but dragging myself out to run or bike just seems like too much, even though I have a few bike rides and running events that I should be putting some mileage in to get ready for. There are career and friendship things going on that have me down. I'm frustrated at my lack of control over certain things, particularly on the job front. I'm doing all that I can, but the economy is making things bad for people in my field.

We all have our up and down periods. Time helps, but when you're just in the dumps, how do you crawl out?