Yoga is recently focused as a way of relaxation in many developed countries. Its character is that you need no serious physical activity. Yoga technique is considered to burn your visceral fat in spite with rather a series of slow movement. It means you can recommend yoga to elder people or patients with physical illnesses.
Here, a couple of studies are introduced in which yoga activity has reduced stress in patients with cancer. Participants felt less fatigued after yoga exercise.
The Guardian: How yoga could ease cancer patients' pain and fatigue
It is unsure this study is a controlled trial. But the in the second study participants were divided into two groups: exercise alone and exercise and yoga. The latter participants showed improved mood compared to the control. If it is a randomized control trial, this result may be reliable.
The mechanism of the effect on the mental activity of yoga is still under-investigated. Some researchers claim yoga activity reduces your cortisol level. But, it is not easy to measure the influence of yoga on internal cortisol.