Let's face it, most people would love to be able to do one easy thing and be fit forever. To much dismay, that may not be the case.
To get where you want to be, a good balance of healthy eating and regular exercise are necessary. It's such a huge misconception when people think if they eat healthy then no exercise is needed, or if they exercise all the time they can eat whatever they want. Here are the problems with both assumptions:
Sure if you keep up with a healthy diet, your body will thank you, but not strenuously using the muscles you have for a long period of time can leave an individual weak. I'm not saying that individuals who do not participate in sports or outside of school physical activities are week. I am suggesting that everyone take thirty minutes out of each day for about three days a week, and take a nice brisk walk, or ride a bike. Other fun activities like dancing, walking your dog, or even bowling can help tone some muscles.
On the other hand, exercising 24/7 with the necessary breaks is great too. However, to have the energy and nutrients to actually exercise you need to eat right! Eating without conciously choosing your foods could get you seriously ill. Not enough vitamin C? You might end up super prone to getting the flu. It is imperative that you eat well.
When it comes to eating well, you have to eat breakfast. It's what fuels your tank for the day. Try a peice of whole grain bread, toasted, with a layer of peanut butter for complex carbs and fiber to fill you up. Eat a lot of simple ingredient foods so you know nothing is refined or processed. Fist sized portions consumed about eight times a day is good for keeping your metabolism up.
Stay away from soda's, too much candy (HALLOWEEN), and other foods that your waistline might regret in a week or two. Lot's of fluids are also essential. Water is just about the healthiest beverage out there. Feeling bored, which leads to hunger, on a school night? Brew yourself a nice mug of green tea to stifle that fake hunger.
The trick is to keep a good balance of nutrition and exercise. Anyone can do it :)