Grit grows as we figure out our life philosophy, learn to dust ourselves off after rejection and disappointment, and learn to tell the difference between low-level goals that should be abandoned quickly and higher-level goals that demand more tenacity. The maturation story is that we develop the capacity for long-term passion and perseverance as we get older.
— Angela Duckworth, Grit: Passion, Perseverance, and the Science of Success

This video shows an incredible example of perseverance from Olympian Derek Redmond.