First of all you have some capitalization errors. I would suggest you turn An example of this would be if you decide to play an instrument, one day you could become very talented and maybe famous to An example of this would be deciding to play an instrument. If you keep practicing (change the word practicing if you wish) you can become successful. . Just try to remove informal words to make it more formal. Other than that I would think its acceptable for a 9th grade essay.
Good luck hope you get a good grade :)