You'll be fine if you really want it. But I know Marine boot camp is hell. It will be hard and it's supposed to be, but if that's what you want, you'll make it. However, be prepared to be punched in the face, choked, etc. I know 2 guys who just got back from Parris Island a couple weeks ago and they said it happened all the time. Plus the fear thing. It lasts, believe me it lasts! But you can make it through! That's the biggest thing. These guys said they saw people wetting their pants in front of the DIs almost every day, literally. But don't let that scare you! They absolutely loved it and thought it was the best thing for them. So if that's what you want go for it all the way!
An edit on the physical violence thing. They can only hit you if you bring your hands above your waist when they are within a certain number of feet of you. So as long as you learn quickly about things like that you'll be fine.