I can do that.

My father was a baseball player. In his small town of Cortez, Colorado and then for a small church college in Rexburg, Idaho. He left for two years to serve his church in Mexico. There he did wildly courageous things. Upon his return he found himself at his little brother's track meet in Colorado. When he recounts this story he says he thought to himself, in a cocky manner, "I can do that."
He just assumed he could do it. Later that week he and his brother took to the track and his brother laughed at the pain his cockiness caused my father. He realized it wasn't so easy. Not that he couldn't do it. He started back up at college in Idaho and was still determined that he could do it. He found where the track team practiced and studied their work out times. Then he did it. He just ran out on the track early one morning. Then he ran out again the next morning. He ran every morning until he was one of the fastest runners on that track. The coaches never questioned him. They never asked his name or where he came from. They just watched. As he proved he could do it.

Months later they threw him a jersey.