We all have those days--nothings going right, there's just too much to do, etc., right? I know I have them!
And how about not having the money (or the inclination) to join a gym? 
I've found lots of good videos on youtube and exercisetv.tv (and if you have On Demand there are some there, too!)--most of them are short, 10 minutes or less, though there are some longer ones, too.
Prevention magazine and most fitness and women's magazine websites have workout routines--some video, some not.
Yesterday I found a site called Slimtree.com that has free 1 and 5 minute exercise videos. There are a lot of beginner ones (I'm going to try the Pilates ones--I've not done much Pilates!) and the ones I've looked at seem to be pretty good! They also have an option where you subscribe and pay a fee and you get longer videos but I can't afford that--maybe in the future.
I've been finding these sites just by searching. There are loads of good short routines out there in cyberspace--just look!
No more excuses!