From the time that we are little kids, music appreciation classes are full of the three B's - Bach, Beethoven and Brahms. In fact, even if you have never listened to a piece of classical music, you probably still have some awareness as to who Bach is.
But Bach didn't just wake up one morning and walk down the stairs a brilliant composer. He started out helping with the organs in churches, many of which were powered by young boys behind the instrument, jumping up and down on the air bags to keep the sound generating through the instrument.
He progressed, as did his composing career. It is believed somewhere around 1705, when Bach would have been about 18 years old, he wrote his famous Toccata and Fugue. (Again, video link to jog the memory - I know you've heard this one).
Nope. He really wanted to move up, to become a musician for a court and so, in about 1717, he created his form of a musical resume - the Brandenburg Concertos. This is a work of six different concertos, each with three movements, that he utilized to show off his composition skills and his ability to incorporate multiple instruments.
Bach didn't get the job. In fact, during Bach's career, he had a falling out with an employer and got jailed for a month because the head honcho was annoyed. No one even knew the Brandenburg concertos existed until after he died. It was a dream job, or so he thought at the time.
In spite of these set backs, Bach went on to compose pieces for 30 years. 30 years? In the 1700's!?! The longevity of his career, the fact that everyone, musical or not, over the last 300 years has known his name is because Bach knew what he wanted. He did not give up and he found his success.
If Bach could make it, why can't you?