If you get to the gym and realize you forgot your sports bra/any type of bra at all and still decide to do a workout (good for you by the way), do NOT do the eliptical machines. While you can move on them in a way that doesn't cause too much discomfort, it does end up hurting your back eventually.
Next time, use the bikes with the straight back seats.
p.s. remember that as an alum you can park in the white lined spots around the gym after 4:30pm and all day saturday.