Do you ever set financial goals for yourself that are higher than what you normally make and work to achieve them? I like to make it something like a game to see just how hard I have to work to make, say, $200 more a week.
I usually make more than the goal I set for myself, anyway. I can't just stop in the middle of work because I've reached my goal, so it ends up being more. And many times there are bonuses added, making it even more.