How do I write a good personal statement for medical school?

"Why do you want to become a medical doctor?"
Where do I start? What do I need to include? How do I make a good impression?

Here is a example of what you could put: I want to become a Doctor because I want to help sick people and people who are in need of assistance or medical care.Our country needs more doctors than ever now with advancement of tech and other things, and I want to help to become to fill the need and to help the Country with saving lives.