Hey there. I just had one and it was waaaay easier than I thought. I was not able to run the treadmill so they gave me the injection that makes your body think it is excersing (spelling?).
You only have to walk- run until your heart rate reaches a certain point and maintains that rate for a certain length of time. I believe that these rates are different for eveyrone based on age/weight etc.
Make sure you wear comfy clothes and shoes.
If they decide to do the injection cause for some reason you are unable to do the treadmill, the tech will explain everything to you step by step (at least mine did).