Author Elbert Hubbard told the story of an incident during the Spanish-American War. It was imperative that the president get a message to the leader of the insurgents. His name was Garcia and he was known to fighting somewhere in the mountains of Cuba, but no mail or telegraph could reach him. Someone said, "There's a fellow by the name of Rowan who will find Garcia for you if anybody can."
Rowan took the letter without hesitation. He sealed it in a leather pouch strapped over his heart. He landed in the dark of night off the coast of Cuba and make his way to the mountains, and after much difficulty, found Garcia. He handed him the letter, turned around and headed home. Hubbard tells this story in "A Letter to Garcia." Rowan didn't ask, "Exactly where is he?" or "I doubt if I can do it." There was a job to be done and he did it.
Instead of making a dozen excuses why you can't complete the task, think about Rowan. Deliver the goods!