I think if you're a decent composer, your material should be a very intimate account of who you are as a person. You will probably never be able to tell what a composer's favorite color might be just by listening to their music, but you should get a strong idea of how they perceive the world around them.
For example, if you ask me to write a very heroic song, I will write something that bears witness to what I think heroism is. You'll probably hear music that will bounce back and forth between melancholy, audacity, and hopefulness because I think courage has to do with being bold enough to face your deepest fears. If you think bravery is fighting a whole bunch of thugs at once or something, you might write something that is forceful, strong, and a bit audacious as well.