The course must be difficult in order to ensure people are at a standard they must be to lead men into life and death.
The only way to test people (short of actually putting their life in danger) is to put them under stress and remove as many of their comforts as you can.
Anyone can be in a great mood and do a good job on a full stomach, full night's sleep, no body parts hurting, lots of time to solve the problem, and no bugs. You have to take those things away in order to see who can still not only pick themselves up off the ground to get the job done, but have enough left over to motivate others to do it.
Long story short, it will be hell and you will probably want to quit sometimes, but if you stick it through and pass you will be more proud of yourself than you ever could have been if the course were easy.