How should i structure a medical/dental personal statement?

A lot of statements that are aimed towards subject based degrees come with the recommendations that 70% should be why you wish to pursue that subject further through higher education, and 30% about who you are too. It's difficult to do the same for a medical/dental statement: you haven't experienced the course or degree contents before.
As such, it is better to structure it 50-50: 50% on why medical/dental school is good for you, and 50% on why you are good for them. What this means is that the first half should emphasise what experience you have, what books and articles you might read and generally pointers that suggest you have made a balanced decision to apply for medicine or dentistry. The second half should talk about your personality, your achievements and extracurriculars, including volunteering, such that it shows the universities what makes you stand out from all the other applicants.