it aint a bad thing if that's what really makes you happy and know it's what you want to be doing long term. the problem is, so many people can be short-sighted and want to live in the moment, and then when you're 30 with no skills, no career, no love, no general content with where you're at, i guarantee you'll wish you had kept more doors open. it's like anything though. know thyself, and strive for what makes you truly happy. when you're young, your interests change so much that it's silly to limit yourself to doing one thing all the time, because when you realize it isn't the be all / end all of your existence, you'll regret not leaving yourself with options.
that's all i try to think of in terms of being mature and doing the responsible thing. yes, it's great to be ambitious and passionate about things like skiing, but you also need to realize that it probably wont give you a career and will only ever be a past-time activity to you, so just keep your doors open. if skiing works out for you, professionally, that's great, just don't bank on it, knowing it's an unrealistic goal.
look at it this way. are you still the same person you were three years ago? i sure as hell know i'm not. i went through so many damn phases growing up, as im sure most people on here have. so what makes you think you aren't going to change again? try not to settle down and be the person you think you're going to be for the rest of your life until you absolutely know. be ambitious, have fun with shit, but also understand that the future you is going to want to kick the current you right in the pants for just doing what made you happy in the moment, cause when that moment passes, buhhhhh.... now what..
sorry, got off topic there. bottom line, do what makes you happy, keep options open, and have your shit together by the time you're 30, cause there's nothing more regretful than pissing your time away thinking you're happy with yourself when it's really only a short-term solution. especially when you only have one life to live and you can never take it back. trust me, my early 20s were a dark time and im not proud of it. worst part is, all the fun i thought i was having at the time, now, looking back, has done nothing to make my life better. a few laughs, a few silly memories, and that's it. video games, facebook, all this shits gonna be long forgotten when you're older and you're going to wish you'd done more of what matters and actually has more of an impact on your life than just satisfying that urge for instant gratification through mindless entertainment.
but of course everyone on here, for the most part, is still young. find yourself, do what makes you happy, and keep an open mind. go try new shit, go meet new people, study hard in school. all things that will contribute to a better, more successful, more fulfilling life in the long run, this is promise you.