If you've ever run a race, you've likely seen supporters holding up signs as they cheer you on. Many of the signs are lighthearted and familiar: "Worst parade ever!" "Pain is just French for bread." "Therapy would have been easier." "All this for a banana?"

But at the TCS Toronto Marathon on Sunday, one spectator held up a sign that stood out: "What a privilege!" It was a simple message, but profound. In the middle of the exhaustion and effort, it may not have felt like a privilege to the runners...