I had a pretty massive weight loss just after college. Kept it off for a long time.
Yes, you've got to reduce calories, increase activity, and drink water. But what you absolutely have to realize is this is a lifestyle change. Don't think of it as a "diet." "Diets" end. This is the new you. This is your new life.
To say "If I could do it, anyone could," sounds kind of trite, but it is the absolute truth.
I look forward to your progress!

(steps down off the borrowed motivational soapbox)