The movie is about a rugby team and that needs motivation. The most motivational lines are the ones of a poem being read out when the rugby team visits Robben Island (a former prison-island a few kilometers off the coast of South Africa, on which Nelson Mandela was once held in). These same lines are also in the theme song, which plays at the beginning of the movie, repeated at the end of it and the music can also be heard in the background throughout the movie. This keeps bringing the message back into the viewer's mind.
In English class I then found out that the theme song was adapted from the poem "Invictus" (which gave the movie its title) written by William Ernest Henley in 1875. Invictus means invincible and this is the theme Nelson Mandela tries to convey. For he was imprisoned for "9000 Days" (also a song-title in the movie), yet did not let anyone bring him down. He fought, he rose - and look at him now: he is a wise, valued man and president of South Africa.
This is so beautiful, you must listen to the voiceover (below) while reading the comic strip of them poem below that. Please, please do.
I hope you like it as much as I do! :)