I saw this amazing vort on last week's parsha. It's from sefer Kol Eliyahu, selected chidushim from the Vilna Gaon. (I will paraphrase. It does lose something in the translation, but I think it is worth a shot):
"Re'eh Anochi nosayn lifneichem hayom bracha u'klalah"
"See I am placing before you today, a blessing and a curse"
It says "I am placing" instead of "I have placed" - which would mean that a person can only choose a good path at the beginning, but once he has chosen a bad path he is stuck with it. Therefore, it says, "I am placing": A person has the chance at any time to choose a good path.
A person might think nevertheless, "what good will it do me to choose good? I have accumulated so many aveiras in my life". Therefore, it says "Today". Whoever does Teshuva should view himself as a baby born TODAY.
A person might yet say, "what can I do if the yetzer hara shall force me to sin?" Therefore the verse says, "Anochi" - I, God Himself, will help; you need not fear the yetzer hara.
A person might say, "What if I'm the only one who chooses good? What is it worth?" Therefore the verse says "Re'eh - See (first person singular)." Choose good for yourself regardless of what the rest of the world is doing.