It's the same with becoming a Millionaire, probio lite so many people give up on their dreams because they set unrealistic goals and quit before they even understand why? Wouldn't you agree that before becoming a millionaire you have to earn your first $100 and then $1000, after you get better, learn more, gain more knowledge and then you earn $10,000 and so on.
Definitely cut out the coffee cold turkey. When you first quit it, you may have a constant headache for about 2 weeks, but afterward you'll feel better. For substitute, drink a lot of herbal teas. There is also a coffee substitute, "Babmu" is the most common brand, you can find it in most health food stores. It's comprised of barley, acorns and figs and tasted quite a bit like coffee.