I agree with everyone else. You do need to be fit, but size isn`t a show stopper. The best thing about the Rescue Diver Course is you`re working with your buddy, and doing it together as a team. Most times you`ll never be alone when and if you ever need to utilize thoses skills to perform a rescue, so you can always get assistance from by-standers, the boat crew, etc. Don`t let your size get in the way of completing something you enjoy. The rescue course has different ways for a smaller person to approach and perform a rescue on any size individual. Take the course, you`ll enjoy it and it`ll give you more confidence overall as a diver. I`ve been certified as a Rescue Diver for over 3 years. Just make sure that when you complete the course that you practice what you`ve been taught. Set up your own scenario`s with other divers and practice in the water, it`s a skill you need to keep current and fresh. Take care and enjoy the course.