However, Keats' training took up increasing amounts of his writing time, and he was increasingly ambivalent about his medical career. He felt that he faced a stark choice. He had written his first extant poem, "An Imitation of Spenser," in 1814, when he was 19. Now, strongly drawn by ambition, inspired by fellow poets such as Leigh Hunt and Lord Byron, and beleaguered by family financial crises, he suffered periods of depression. His brother George wrote that John "feared that he should never be a poet, & if he was not he would destroy himself." In 1816, Keats received his apothecary's licence, which made him eligible to practise as an apothecary, physician, and surgeon, but before the end of the year he announced to his guardian that he was resolved to be a poet, not a surgeon.