Get a rebounder (mini-trampoline) or just turn up the music and dance around. Do jumping jacks, pick up a little kid and run through the house, vacuum like your mother in law is coming over in 5 minutes, whatever it takes to get your circulation going. It only takes a couple of minutes to warm you right up. And the effects last. When you get cold again, get up and repeat.
I found out about this by accident. I hated getting out of my nice soft bed into the cold cruel world at dawn, but I found out if I just hop onto my rebounder, in a couple of minutes I'm stripping off all my clothes because I'm too hot. I keep it right smack in the middle of my living room too, a silent reminder in my ongoing struggle against inertia.