Help!

I'm not feeling motivated to be healthy at all right now.  Here's the deal: when I first woke up this morning it was snowing.  Then my walking buddy called and said she'd have to bail because her daughter is sick.  (Totally valid.)  I was still planning on going on a walk with the big O this afternoon though.  But first I needed to pick up some things my mother in law asked me to send her so that I could mail them when I went on my walk.  Well, things took a little longer than I planned when I made an extra stop at the bank to make our car payment. (Good thing I remembered when I drove past it!  I almost forgot.  And it was due today.)  When we got home I fed the big O and hurried and changed her diaper and got her dressed in her warm snow suit thing and headed out the door... only to realize that it was totally dark already.  So I came back inside and waited for Bryan to get home from his class.  Then around 7pm I had a Relief Society activity, but I planned to go to the mall afterward to return some pants I got for Bryan that didn't fit him very well and I figured while I was there I'd walk laps around the mall for a half hour.  What was I thinking?  Even if the big O had remained happy during the RS activity (which she didn't), it still would have totally been her bed time by the time we got home, not time to go to the mall.  Well, now the big O is asleep in bed and Bryan is dutifully working on his homework and it's cold and dark outside and warm and cozy inside and all I want to do is change into my jammies and watch a movie and eat some cookies.  Obviously I'm not going to do either since I'm not eating sweets and since Bryan would get totally distracted if I watched a movie, but... I am really not in the mood to work out.  Any great ideas for something good I could do inside my tiny little apartment that would be an acceptable work out, but wouldn't cause me to work up a major sweat?