I have been trying to find this book series that I read around the mid-2000s.
It contains people being sent to a college or some such to learn how to use magic. There are possibly 5 elements, one of which is fire and another is something like emotions.
There was a trial that the people have to go through, with a scene where they had to cross a bridge while being barraged by strong thoughts of fear or something like that.
Possible conflation, but I seem to recall one of the characters talking about how to cope with the hot weather, to take a warm bath instead of a cold one so that the body will heat up and make the surrounding air seem relatively cooler.
Another detail was that one of the characters worked really hard at their magic and improved, but the other people in the school all thought he figured out some trick, and were trying to get him to explain it to them, which made him really annoyed.
The last line of the first book was something about how, instead of writing the story years after it had happened, they are writing it as it occurs.