Is that a serious question?Fitness is essential to a healthy body in every aspect except spiritual wellness. Fitness improves the quality of living hands down. A proper fitness helps blood circulation, improving cognitive ability and grogginess, also improving cholesterol levels, and increasing the metabolism. You can remove waste from the blood quicker and get your heart in better shape. Tone your muscles, increase your self esteem and endurance. You're body is a machine that needs to be taken care of otherwise it will not operate to its potential. Fitness is the equivalent of maintaining optimum performance for your bodyAlso, fitness improves mental issues such as depression and anxiety and other sorts of mental issues. By exercising your body produces endorphins that improve your mood and attitude. No one should consider fitness a chore, it should be a top priority that you can't function without, there are no negative side effects to fitness, just get out and start.