Can I be a gymnast and a YouTuber at the same time?
That being said, the larger challenge would actually be time management. Being a full time Youtuber and doing gymnastics means you will be constantly busy. Are you ok with essentially working all day every day to make both goals attainable or would you prefer to have more time for rest and relaxation? Keeping up a busy schedule is energizing and exciting at first, but can become a massive drag once you've been doing so for several months straight.
The short answer is yes you can. That said, both of these areas require a great deal of time and dedication to be successful. I know two professional YouTubers in the local area and am amazed at how much time and thought goes into the production of each YouTube post. It really is a full time job for these people. Gymnastics of course has its own challenges as only the upper echelon of participates even make a career out of it. Having multiple interests and hobbies is a great thing, But be aware that turning an interest into a profession takes a great deal of time and commitment.
Absolutely! You can do anything you put your mind to. Everyone is starting YouTube pages and generating a following. You can record and post videos of yourself doing gymnastics at a gym, a studio, etc.
It is not hard at all, just get someone to film you and you got it made.
Be thinking about what content you want to put in each video - tutorials, full routines, arts and crafts.
It is all on you.
Hope that helps.