It's only hard the first 8 weeks while trying to re adjust to everything. You have to learn how to power through physical/educational activities with barely any sleep while being uncomfortable(wet or dirty). I would say the hardest thing to get use to is the body detoxing from all the junk food you use to intake in the civilian life. As long as you aren't weak minded it's not that hard. But for something like being a sniper or special forces, all I have to say is good luck man. You will definitely need it. Edit: You have to be selected or sent by your company to sniper school. I forget how long the school it but I know a lot of people drop out due to the difficulty of it. Let's just say if you can sit in your own shit/piss you won't pass.