Let's start with some quick hitting, practical points for you, in case you're in a hurry -
1. I think sugar takes a while to quit for most people, and some preparation.
2. Start slowly learning foods you like and trying new healthy foods to find a mix you like. When you go to the store, try one new healthy food to see if it suits you each time.
3. You're going to need to replace all the sugary and junk food you eat. Quitting isn't enough - you need something else to take its place.
4. Consider tracking your energy levels throughout the day for a few weeks and what you eat. It takes a bit of effort, but it's massively worthwhile effort. You'll learn what you respond to and have a massively higher quality of life.
On Kevin Espiritu
I've been very successful in my quest to eliminate hardcore competitive video games from my life. By using Stickk, a friend, a monetary incentive, and accountability, I've hard-quit League of Legends and repurposed the hours a week that I was spending playing games.
This next year is going to be very exciting for me, but is also going to require a lot out of me as a person. It is going to require me to become a different person if I want to have what I will consider a "successful year."
There are no financial, travel, or social goals planned for 2013 at all.
Instead, I will call 2013 the Habitual Year. The only true "goal" that I have for the year is that I commit to implementing or quitting one habit per month using the framework that has worked so well for me this past month. The way I see it, if I implement or remove a total of 12 major habits (think nutrition, exercise, meditation, socializing, etc) then 365 days from now there really is no way I can have a bad year.
I need to focus on habits that other people can easily see if I have accomplished or not. For LoL, it was easy because there are 3rd party websites that track gameplay, allowing Jon to see if I'd played or not regardless of if I wanted to tell him the truth. This needs to be the case in any future habit challenge.