Eating healthy can impact your life multiple ways. You can avoid getting obese, heart disease, and other irreversible diseases. You will be able to do better at your job/school because you can focus and have more energy. Your friends will want to be around you more because your mood will be improved and you'll be less stressed.
Overeating and eating the wrong portions of food are the main contributors to obesity and other food related diseases. Once you start eating healthy and eating correct portions of the food groups you are already reducing your chances of getting heart disease, having a stroke, and having diabetes. These diseases affect your everyday life and by the time you get them it's already too late to change your lifestyle.
Your performance and grades in school will improve significantly due to your increased energy and focus caused by eating healthy and exercising. At the end of the day when you go home you won't immediately want to lay down and sleep. You’ll want to go out and do more. Eating healthy improves your mood and stress levels. If you're not always grumpy and stressed out your friends will want to be around you a lot more. Your overall quality of life will improve.