Post-wedding weight gain... need to drop 10lbs!

After my wedding this past October, my husband and I were left with an enormous chunk of red velvet cake in the fridge and several bottles of champagne. We spent the next several weeks enjoying those two things for dessert. Every. Single. Night. Of course he didn't gain an ounce but I did... about 7-8 pounds.

Also now that it's winter I can't enjoy my daily runs outside. I sort of hate treadmills but I may not have a choice... join a gym? Any suggestions on how to get my act back together (and my pre-wedding weight!) ?

Many thanks!