Being an Apologist _ You do not use your personal statement to explain why you lack certain skills or experience. The point of writing this short paragraph is to sell yourself and this involves highlighting your strengths instead of apologizing for your weaknesses which in itself is a sign of weakness. The time and place for discussing flaws in your suitability is the interview and at that point, you must focus on how you plan to overcome any holes in experience/skills etc.
The reader of your medical school application is expecting a degree of proof and really wants to know how you know. It's not enough for you to say you want to help people. How do you know what you want to do in medicine, what have you done that leads you to know that? How to write your medical school personal statement: Persuasion The most persuasive way to answer this question is by sharing experiential knowledge. You would say to an admissions official in conversation, "I know because I've done it. That's how I know. And I can give a specific story."