How do I get 3 months off from work?

I am 22 years old and currently work at a factory manufacturing combines and making around $40k a year. I've worked here a little over 3.5 years. It's a decent job and everything but has bad working conditions and can be very stressful at times. I've saved up some money and want to take 3 months off from work if I can. I understand that if I can get 3 months off I might not get my job back but I'm okay with that as I have enough saved up to find another job - even though it's likely I would get my position back since they like to hire previous employees back when they leave for other reasons. I just want to be able to take time off and travel around the US (and or world) and enjoy life and have new experiences. I really could care less about my job itself but I do like the extra money coming in and friends I've made there otherwise I would probably just quit and take as much time as I want traveling and look for another job when I'm done traveling. So my question is how do I go about telling my boss I want to take 3 months off? Also what if after the 3 months is up and I realize I don't want to go back to my job? Can I just up and quit?