If you are looking to get fitter or to lose weight then you need to look at your diet and also your exercise regime. A healthy weight is often achieved by combining the two and if you do one without the other you may find that you suffer from other health issues. Fast diets, for example, can be detrimental to your health and over exercising without eating the right foods can also cause negative health implications.
If you are serious about getting fit, then you may wish to see a personal trainer who specialises in exercise and nutrition. They will often be able to write a program for you based on your current lifestyle and health that will guide you as to what you should be eating and when and how much exercise you need to be doing.
If you are someone that does not normally do a lot of exercises, then you will need to start off gradually to try and build your body up before going at it full force.
Healthy eating is all about a balanced diet. Making sure that you are getting enough of the right sorts of foods and that you have all the vitamins your body needs to function correctly.