High school student loolking for medical career?

Im a high school senior and i would love to get into the medical field preferably dentistry or physical therapy. I would like to shadow one of these two job areas, but I dont where to start. What can I do over the summer to get involved in one of these two area, I want to start preparing now and learning more. Is there anyone that can help me with information or advice on what i can do over the summer to start getting involved. Any help, tips, or info would be hight appreciated. Thanks so much!