yep, you have to stay mobile...if its bad then immediate rest is needed but if there is no serious problem to prevent it, you should get moving as soon as you can (even careful walking with the best posture you can manage)...the type of mobility/exercise you employ will be dictated by your specific problem...this is where your medical professional comes in...for example, if i ride a bike or run or do anything that can encourage further extension, i'll be back in bed...