They all be pickin' my brain, yo!?

Hey, I studied and earned every bit of knowledge I have through studying and life experience. I have a position in an office environment where my expertise and learned experience is increasingly in play and in high demand. In other words, people are constantly asking me "how do I do this?" or "can you help me do this?" and I've found that this is nothing more than laziness, and feel that I am being taken advantage of because it's easier to mooch off my accomplishments than to try and discover their own. I'm getting really sick of it, and am considering telling them all to stop picking my brain, or either start paying for my time. How do you guys feel about this. Any honest answer is welcome. Thanks for your opinion.