If you have reservations about health conditions, always check with your physician before you start any exercise program. I'm too tired, too stressed. When I'm not so fatigued, I will begin. That' s another excuse. You might call it active meditation.
Exercise also normalizes glucose metabolism, which provides a steady supply of energy to the brain.
If you develop a well-balanced health and fitness program, you will have fewer aches and pains, be better able to deal with stress and feel less tired. Most weight loss from diets without exercise will be short term. As soon as you resume your normal eating habits, the weight generally returns. If you work a muscle over and over, you will rid it of its excess fat. Exercises for specific body areas will firm the muscle, but the excess fat removal comes from aerobic exercise and a decrease in caloric intake.