challenge on radio waves

driving down a back-country road the other night, i caught the tail end of an alistair begg message on the radio. you know that token announcer with the deep, pleasant voice they always have? the music fades the preacher out and the m.c./announcer/radio-dude comes on and wraps up the program? generally, i turn it off or mentally tune out when he comes on, which i started to do once pastor begg was finished...but the m.c./announcer/radio-dude/whatever-you-call-'em asked a penetrating question that made me do a double-take. i hit the power button on the radio and repeated his question out loud to myself,

do i do what i do for the sake of the gospel, or do i do what i do for my own sake?

i still can't shake that question...