Sitting here....at my desk.....procrastinating on the TE forums I'll trade ya!

In all seriousness, my rule of thumb for these days is this: Go out for 10 minutes, 1 mile, whatever. If, after that 10 minutes, you're still miserable and unmotivated, it's ok to go home. I'm not a pro, I don't get paid to ride, so I want my time on the bike to be fun. If I'm not feeling it, it's ok.