Recently, I heard an excellent analogy to the attitude of a karma yogi.
Imagine that in a 5-test series, one team has already won the first three. They have practically wrapped up the series. So what is their attitude in the 4th test match? They are happy and satisfied because they have already won the big event and even losing this match can be taken in their stride. Yet they still strive to put in a good performance, maybe break some records for the books. There is no tension on their face and they respond to the other team's desperate sledging with grins!
The karma yogi knows that he is complete already, a winner of the series. Various things may please him and he will put in full effort for them but he is not tense about getting or not getting them. He does not build his own image out of ther people's comments. He is smiling inside.