Stress
Don't expect every day to be a chill hangout with the who's who of the world.
When you're first breaking into the field, there's going to be major stress, mainly because you won't be making any moolah. Actually...
Unless you're still living with mom and pop (which brings a whole other kind of stress), you'll have to be working some other job to pay the rent and to keep you in frozen pizzas. So basically, you'll be working two full-time jobs, one of which you'll be doing for free. Um...yeah, that's stressful.
If you actually manage to break into the business, you'll experience a whole new kind of stress. Fashion photographers are usually freelance artists, so it's up to you and only you to keep those jobs rolling in. With masses of other people out there trying to do the same thing, you're going to have to constantly hustle to make it work. The good news is that if you do actually manage to pull this off, you'll be one of the very few people who can say they actually love their job, which just might make all of that stress worth it.