One of the best things for someone to do when he wanted to be in shape is to keep moving. This has been proven to be effective. Exercise in any forms is one good way to do it. Walking and some dancing are another way to do it too. Engaging ourselves in active physical activities is all helpful.
Also, make sure that you complement it with proper diet. Eat healthy and get s healthy lifestyle too. There is no other way to keep in shape but to stay healthy. If you can do this, then you will be in good shape for sure. Try it out for a month or two and you will see good changes in your body.
You can easy diets for more information regarding losing weight and keeping in shape.