Any good workouts to do in your seat or while walking around?

So I lead a busy life. I work early mornings at a call center (hey, I'm a poor college student trying to pay for school!) and I have to juggle music practice and my boyfriend. It's gotten to the point where I have no time for exercise. I'm not huge... but I have a goal to loose 10-15 pounds this summer. I have two and a half months to go and I'm not going anywhere... are there any good workouts to do in a char? (while I'm working) or any ways to workout extra without looking weird just while walking around and such? I know, weird question but any advice is appreciated! thanks guys!