The persons who suffer from CFS are almost always in a vicious downward cycle. They are fatigued with muscle pains and they have been getting a great deal of rest. A cycle develops whereby rest leads to muscle wasting, which leads to decreased performance, which leads to pessimism, which leads to disinterest in exercise, which in turn leads to even more rest.
Daily exercise can end that downward cycle and replace it with an upward, positive cycle.
When a person exercises, a new cycle develops consisting of exercise that leads to muscle enlargement, which leads to increased performance, which leads to optimism, which leads to interest in exercise, which in turn leads to even more exercise. Studies have demonstrated that exercise has anti-anxiety and antidepressant properties. Of course, exercise is also beneficial for the cardiovascular system. Exercise must be started slowly and increased gradually. If a person is generally fatigued and is not in physical fitness, limit the exercise to what can be tolerated.