If it's in writing, then yeah, you're asked about your hobbies so people can get a better picture about you and what you enjoy doing in your free time. I never mention it as a hobby IRL though - if you say you go to the gym and lift weights, and you don't look like you lift weights, it's a bit awkward; conversely, it's a confidence booster when people know you go to the gym without you having to tell them, because you look like you do.