If you have a doctor's order that you are to be assigned light duty assignment at work due to a physical condition that you have, you must be accomodated within reason with such light duty assignment. There is a Federal law called "Americans with Disability Act" requiring accomodations at a place of work by your employer when the employee has substantiated medical records requiring such.If you do, you need to speak with your supervisor or human resources department about the situation and your medical condition. Make sure you have doctor's orders in your personnel file saying that you need light duty assignment if your medical condition warrants such.If your employer still refuses to accomodate your condition, then you need to meet with your labor department about it, make a formal complaint and perhaps retain a labor law attorney because of your supported medical condition requiring light duty assignments at work.