How can I quit coffee?!
You should probably start by replacing coffee with some healthier.
For example, instead of coffee just buy a V8 or something like that. There's not only vegetable V8's, there's a fruit one.
Just drink less and less each time until you're over it.
Are you opposed to the caffeine or just coffee in general? If it's caffeine, you can try mixing 1/2 decaf and 1/2 full strength to gradually decrease the withdrawl. Water will actually keep you awake if you are fully hydrated. Also, try getting up and doing a few jumping jacks if you find yourself getting tired.
Just take another energetic drink and quite coffee easily.