But the comparison is not exact. In fact it is very misleading. Because while the friends holding up the chair is a good picture of grace, it was the man's tremendous upper-body strength that got him across the finish line after 26 miles, and his friends had nothing to do with that. That strength came from him not them. But grace is not like that.
Grace sustains everything in the Christian life.
It holds up the broken chair. It gives the upper-body strength. It prevents other obstacles. It keeps his heart beating. It keeps his eyes seeing.