You are what you eat. If you eat junk, it will be reflected in your health. If you don’t exercise, you will lose muscle mass and calcium density in your bones.
The top 10 causes of illness and death in the US have a nutrition component and many have a lack of exercise component. Maintaining a healthy weight and getting regular exercise (30 minutes per day, 5 days per week), can prevent many illnesses. So if you want to live a healthier life, eat healthy foods and exercise regularly to maintain a healthy body weight.