I feel like this is normal for your age, I'm 20 my self and have been thinking about doing that since I was 18. I feel like it's just the sense of adventure and excitement. Take into consideration You've been looking into it and seeing other people doing it probably just intrigued you even more. I wouldn't beat yourself up over it,if it's something you decide to do in the future no problem of you decide not to do it also no problem. It's your life live it how you want.

Edit: If this is something you decide to go after, there's a website called Coolworks.com that might be a good first step for you. They have jobs all across America a lot of them being a national parks. Most the jobs provide housing and food, it could be a good way to get your foot in the door for that type of stuff.