Do the thing you fear most and the death of fear is certain.

 Mark Twain (1835-1910), American author and humorist. 

"Do the thing you fear most and the death of fear is certain."

Mark Twain

Samuel Langhorne Clemens wrote under the pseudonyms Sergeant Fathom, Rambler, Thomas Jefferson Snondgrass and W. Epaminondas Adrastus Blab before he began using his pen name Mark Twain. This name comes from his years working on Mississippi riverboats, where "mark twain" meant "two fathoms deep".