As others have said, time is huge. I met a trumpet student of a French superior conservatory once and tallked about how it was like to study there. In summary, it was like 8 hours a day, 5 days a week, with the expectation you'd do as much during the week-end. Most of that time was playing time. There was once a famous violonist who was accosted after a concert by an enthusiastic lady who told him "I'd give my life to play like you." To which he responded that he did give his life to the violin.