An important thing to remember with marketing is that it's not like a wage slave job. You're not swapping an hour of your time for a given rate of pay.
At *best* you're doing work today that you'll get "paid" for eventually. A week from now. A month from now. A year from now. On a more positive note, it's also work that you might get paid for more than once (unlike that hour of work).
I'm not sure if that's supposed to be encouraging. But after a while you get used to it.
-David