It depends on the size of your firm. Typically, a human resource managers work in the least stressful ways compared with other departments such as sales and marketing. The most notable factor for me is that most of the firms have already outlined their HR policies such as compensation policies for employees, hiring and firing criteria, training and other popular areas in management. I don't call it a stressful task, but yes you have to creative, diligent and forward-looking. Some institutes and bodies take further steps by helping HR professionals in dealing with HR task seamlessly in CIPD and other courses. You can try some of those if you are still worrying about stress and workload.