Everyone loves to say that Ranger School will push you to your limit, but we don't often get into what that means. So let me share a secret -- Ranger School will push you to your limits, again and again, until you fail or succeed.
Many people who attend hit their first limit in the first day or two. Although we can all run the 5 miles, or do the CWST, or crush a buddy run, it becomes a lot harder when each event is back-to-back, with little opportunity for physical or mental rest.
The first limit comes when you say to yourself, for the first time, "what have I gotten myself into." It is a mental limit, and one you can easily overcome by remembering why you are there and what you hope to be by graduating.
The second limit is when you feel deep and genuine exhaustion for the first time. Until Ranger School, I had never been so sleepy deprived that I would pass out while standing up. I never hallucinated from being so tired, believing that a guy pulling a black garbage back out of his ruck was playing with a dog. I never rucked and then suddenly found myself walking into a tree, barely remembering the past few minutes (or was it hours?). You will get there, and when you do it is far harder than simply being burnt from too many pushups. Your body and mind want to shut down, and will sometimes do so without your permission. Just accept it, and drive on. Remember that all you have to do, in the end, is put one foot in front of the other.
The third limit is, for many, the hunger. I lost 35 pounds in Ranger School, and remember how hard it was to stay warm without anything in my system. You could smell the ammonia of everyone's muscle tissue burning up, and licking out the MRE bag was perfectly normal. But food will come -- you'll get the occasional golden walk with some extra chow, or you'll starve through 5 days and make it back to those Mountain blueberry pancakes. Just remember that everything is temporary except earning the Tab, which you'll have for long after the hunger.
The fourth limit, and the worst at times, is the mental game. Can you shut up and let someone else lead? Can you be a team player even when you have no patience left? Can you follow a nonsensical plan? And can you do it all without pissing off everyone else in your squad? When you get overwhelmed enough, and tired enough, and hungry enough, your deepest self will start to show through. You may not like what you see, and it may distract you from the task at hand. Remember that part of mental toughness is being able to set aside a temporary emotion to focus on the larger goal.
In the end, Ranger School will push you to multiple limits multiple times. Every time you feel yourself hitting that wall, just put one foot in front of the other and it will pass. Once it does, take a deep breath and think to yourself "okay -- ready for the next one." Make it to the end, and you'll find that most "limits" are self-imposed.