The most challenging part would be the clients. Our patients do not walk in the door themselves. Often clients will decline your recommendations and you have little choice but to watch the pets go through unnecessary pain. However there are those clients who will want everything to be done when you know that nothing can save the pet and both can be devastating emotionally.
Then there is the student loans. I would advise you to gain some experience by shadowing your local veterinarians, and talk to them on a personal level. I would still highly recommend this profession, but I also want you to make an informed decision.