If I had to convince my parents this I would tell them about how many people have tried and done this sport and no one, or at least a very small proportion, has injured themselves seriously doing this! Furthermore, I would tell them that being physically active leads to a good routine which is important later in life. I would also mention that doing sports improves quality of life and that without it my quality would be worse. Another thing that can be said is that doing sports can help with bodyweight and self-esteem.