I find these (almost constant) topics a little funny. Like, what are you going to do if we tell you it's the shit and it sucks? Are you going to put your release in based on an online (though well informed) forum? I can see the memo now "on recommendation from Army.ca I'd like to submit my release from the CF".
Seriously, to prepare mentally? Every person interprets a situation differently. One person can snap from ironing but have no problem with morning PT. Another may absolutely HATE being marched around like a child while he loves getting jacked up for uniform issues that he won't change but most likely be fine the next day (psych warfare much?).
Just saying... if you joined the military I am going to assume you might have seen a movie or two in your time. Did it look scary? It might very well be. Do, or do not. There is no try. Enjoy battle school or don't, we can't tell you how you'll interpret it.
/end rant.