Having spent my fair share of time in the customer service world, I can safely say that my attitude towards the folks at McDonalds, Starbucks, Target, etc., get my nicest face, even when I'm not feeling up to it. Usually I ask how their day is going, how long they've got until they get off, or if it looks like a rough day, how they're handling the stress. The other day, a friend and I actually asked for the manager at a restaurant so we could lavish praise on a particularly kind waiter...and he was really surprised, which is kinda sad.

This kind of behavior can often earn you a little something extra--an employee discount or a free dessert--when you're not expecting it. I don't do it for the free stuff, but occasionally it happens. And being nice generally makes one feel good!