Instant

There was a time that I used to think about that thought very often:
"Everyday, God gives us a moment that it is possible to change everything that makes us unhappy. That magic instant is the moment when a simple "yes" or "no" can change our whole existance".

(from the book Na Margem do Rio Piedra Eu Sentei e Chorei, Paulo Coelho)

What is that instant today?