We all know that the key to being happy and healthy in life is in making smart decisions about what we choose to put into our bodies and what we eat on a day to day basis.

This is particularly true when it comes to athletes, who are often more physically active than other people and therefore need more nutrition and sustenance to keep them going.

Whether you fancy yourself a bit of a pro at the tennis club or just like to have a hit around with friends, taking some time to think about your diet can make a big difference to your game.

Different sports and various training routines will strain your body in different ways, so a diet that is right for one type of athlete might not be right for another.

For example, Olympic swimmer Michael Phelps used to cram in about 12,000 calories every day just to keep his body fuelled for all the various training runs and competitions he would compete in.

To give you some idea of what that sort of eating plan entails, Phelps' average dinner would be a whole pound of pasta with sauce, another whole pizza consisting of around seven slices, and a few energy drinks on top of that. Yikes!

Even the most vigorous of tennis players would struggle to win many tennis tournaments on a diet like that. Instead, they want to opt for something a little more balanced.

Optimum Tennis recommends maintaining a good diet not only during the build-up to your next tennis competition, but also before, during and after matches and during trainings as well.

The diet of a tennis player should consist of high carbohydrate foods and protein in order to reduce muscle fatigue and boost endurance, as well as plenty of vitamins and minerals to keep them going.

You will want to drink plenty of water as well, especially when out on the court in the hot Sydney sun, as dehydration can set in quickly when you are locked in a competitive game.

A good strategy for people of all ages and physical ability is to keep the food pyramid in mind when thinking about what they eat. This simple guide gives you a basic rundown of what foods you should eat often and which you should eat sparingly, to help you ensure your diet is on track.

Of course, the right diet for one tennis player might not be right for you, as your individual needs will vary based on body composition and genetics, so it's worth talking to a professional if you really want to ensure your eating schedule is up to scratch.