If you love what you do, you'll be your best at it compared to anything else you might have chosen as a career. Or at least you will love it more, and you won't lead a depressed day of your life.
At least he had Annabeth. They would find a way out of Tartarus. They had to. He didn't think much of fates and prophecies, but he did believe in one thing: Annabeth and he were supposed to be together. They hadn't survived so much just to get killed now.