Those whose illness appears stable may gradually increase activity and exercise levels, but according to the principle of pacing, must rest or reduce their activity levels if it becomes clear that they have exceeded their limits. Use of a heart-rate monitor with pacing to monitor and manage activity levels is recommended by a number of patient groups, and the CDC considers it useful for some individuals to help avoid post-exertional malaise. Energy envelope theory Energy envelope theory, considered to be consistent with pacing, is a management strategy suggested in the 2011 international consensus criteria for ME, which refers to using an "energy bank budget". Energy envelope theory was devised by psychologist Leonard Jason, who previously had CFS. Energy envelope theory states that patients should stay within, and avoid pushing through, the envelope of energy available to them, so as to reduce the post-exertional malaise "payback" caused by overexertion. This may help them make "modest gains" in physical functioning. Several studies have found energy envelope theory to be a helpful management strategy, noting that it reduces symptoms and may increase the level of functioning in CFS. Energy envelope theory does not recommend unilaterally increasing or decreasing activity and is not intended as a therapy or cure for CFS. It has been promoted by various patient groups. Some patient groups recommend using a heart rate monitor to increase awareness of exertion and enable patients to stay within their aerobic threshold envelope. Despite a number of studies showing positive results for energy envelope theory, randomized controlled trials are lacking. Exercise Stretching, movement therapies, and toning exercises are recommended for pain in patients with CFS, and pain medication is also suggested. In many chronic illnesses, aerobic exercise is beneficial, but in chronic fatigue syndrome, the CDC does not recommend it. The CDC states: Counseling The CDC states that counseling may help patients cope with pain caused by CFS, and that talking with a professional counselor or therapist may help people to more effectively manage the symptoms that affect their quality of daily life. Nutrition A proper diet is a significant contributor to the health of any individual. Medical consultation about diet and supplements is recommended for persons with CFS. Persons with CFS may benefit from a balanced diet and properly supervised administration of nutritional support if deficiencies are detected by medical testing. Risks of nutritional supplements include interactions with prescribed medications. Treatment Cognitive behavioral