Journals and Letters of the Rev. Henry Martyn, B.D.
Henry Martyn led an amazing, albeit brief, missionary career through India and some surrounding countries. Although he died at a young age, he managed in six years to "translate the New Testament into Hindi and Persian, revise an Arabic translation of the New Testament, and translate the Psalter into Persian and the Prayer Book into Hindi." He was no slacker!
I stumbled across this site today while researching his work that contains his journals in full. Here is a good thing to bookmark and read - especially when discouraged or disheartened!