Holst's first instruction came from his father, Adolph, a piano teacher, who also made him take lessons on the violin and trombone; the father believed that these studies might alleviate the youth's asthma.
By age 12, the young Holst was composing, even dabbling in orchestration; in 1888, he won a prize in an amateur competition for his vocal work, A Christmas Carol. Thereafter he sang in the All Saints' Church choir and played violin and trombone in its orchestra. In 1892, he traveled to London and heard a Covent Garden performance of Götterdämmerung, led by Mahler. The experience opened up new compositional vistas for the young composer. Holst entered the Royal College of Music the following year where he met fellow student Ralph Vaughan Williams, who would remain a close lifelong friend. Shortly after his arrival in London, Holst found that the neuritis in his right arm, which had afflicted him in his early youth, had worsened and now caused him to abandon ideas of a career as a concert pianist. In 1898, Holst left the RCM to take a position in the Carl Rosa Opera Company as rehearsal pianist and coach. He completed his Cotswold Symphony in 1900, and its premiere in April 1902 was a success. On June 22, 1901, Holst married Emily Isobel Harrison, whom he had met in a choir he had directed a few years before.
In late 1903, Holst took on a teaching position at James Allen's Girls' School, in South London. The following year he acquired a second post, the directorship of music at St. Paul's Girls' School, which he would retain until his death. He added another teaching post at Morley College in 1907, bogging him down and leaving little time for composition. Still, the St. Paul's Suite, written during this period (1912-1913), is among his most often-performed works.
In 1914, Holst began work on what would become his most popular composition, The Planets. The war years were extremely productive, as the composer not only completed The Planets, but also wrote Hymn of Jesus. In spring 1918, Holst began educational work for the YMCA at its various facilities on European battlefields.
He returned to London at the end of June 1919 and took a prestigious post teaching theory and composition at the RCM in 1920. The composer's fame was not only growing domestically in the early 1920s but internationally as well, as works like the Hymn of Jesus were receiving regular and acclaimed performances. By 1924, Holst's health was clearly declining, and he thus lessened his workload.
Beginning in late December 1928, Holst made a series of trips abroad that included visits to France, Italy, Sicily, and the U.S. In Boston, a duodenal ulcer was diagnosed in 1932. On May 23, 1934, he underwent surgery for the ulcer, but died two days later.