Hi Haley,
I have been sitting on my butt now for over a year now, ever since my first son was born. I just felt like I was too busy to take on the added responsibility of working out. I was always involved in organized sports prior to kids, like soccer or softball, but when you don't have a babysitter it's hard. So what I've done is found a gym that has a daycare and I take the kids there with me. My goal is to work out twice a week (that's all the time I can put aside for working out right now) and it's been going well so far! I do the eliptical machine for 30 mins and then I do weights afterwards.
My motivation was that I wanted to feel better about myself. Plus, with the colder weather here I'm not working outside as much and I really was feeling couped up in the house all the time. I want to be in better health for my kids and for myself. My motivation was really being able to feel good about myself and not feeling guilty when I come home and sit on my butt at night. Now I can do that without feeling bad because I'm working out.
But I think you have to find something that you like. Do you like classes, like step classes, kickboxing, etc? Maybe that would be fun for you. I love doing those types of classes and that really motivates me. Hopefully you can find something you like!