Good cardio exercises with a fractured foot?

I am pretty sure I fractured my foot, going to my dr. on Monday for x rays. I am not able to walk comfortably, let alone run like I usually do. What kind of cardio exercises would be good for me to do? I'm an active 20 yr old female and hate to have an injury derail me from my running. :( I really want to keep in shape as best as I can till I heal, though! Help! Thank you :)