I'm too ill to work'. The more an ill or injured worker is accommodated, the better it is for overall workplace morale. Other employees see the proof that, should they ever suffer an injury or illness, the company would make provisions for them, too. Moreover, most employees want to return to work, particularly after the first few weeks of being home have gone by. It's also a social outlet, a place where you become stimulated with new assignments or opportunities for learning.
Every day there are new interactions and challenges.
Work provides structure to someone's life. When you take that away because of illness or injury, the individual loses a part of their structural foundation. Just as an athlete who stops training is no longer in peak condition, workers who cease doing physically demanding tasks lose the required body strength. Returning to work with modified duties, as approved by a physician, can help an employee to recover lost strength and to build stamina. For example, a disability management specialist could ethically work with physicians or rehabilitation professionals on behalf of the employee, whereas a human resources person should not have access to an employee's medical records.