Find a gym or a studio that offers babysitting, and sign up for a class -- any class -- because 45 minutes once a week will give your mommy brain a break and make the week's other 10,035 minutes easier on your tired body.
Go see a flick. Take in a matinee with your baby, sitting near the exit in case she fusses. The number one thing: Choose a movie you really want to see, because before long your movie viewing will be subject to another (little) person's choices.
Brave the cold, and go outside for a walk. Babies in Sweden survive. Just bundle up and walk like your life depended on it -- doesn't matter to where, really.