Paul does not here speak of any special virtue of his own compared to that of others. He speaks of the task he received personally from Jesus Christ; the task of preaching the gospel to the Gentiles. Work is noble because it is God's gift; an expression of his grace. This includes all work--manual, work, clerical work, professional work--when it is done with the gospel in mind; when it is done to enable the work of God in the earth.
I'm busy working on my blog posts. Watch this space!