Consistency is King.
I don't think you'll get too many people to argue with that statement. At least not in terms of nutrition and fitness. And while there are many individual components of lifestyle that you can apply consistency to, I'd like to focus on one that's not likely at the top of your radar: learning.
Jamie over at That Paleo Guy just did a brilliant blog around the notion that you have to take the time to learn how you as an individual tick ... with specific regards to nutrition and exercise. Definitely go and read that piece over as I'm basically just going to add my two cents to it here.
The key is to continually learn about how you personally respond to what it is you're eating and how you're exercising. And sleeping. And how you handle stress etc, etc. The point is, take in as much information that is feasible for your situation and then start applying what makes the most sense to you and fits your lifestyle. There is no one size fits all approach as we all respond in different ways, and are in different places.
By consistently learning and applying, you will start to take control of your own health. I think a lot of people initially have analysis paralysis and freak out over the subjects of nutrition and fitness. They are convinced there is too much information, it takes too much time, and either want to give up before they even start or perhaps hire someone else to plan these things out for them. Or read somebody's book and just follow the steps. It may seem daunting, but you don't have to learn it all at once. As a matter of fact, you can't learn it all at once. This is an evolving process where we are all figuring things out together and helping each other along.
I believe the more you become a participant in the nuts and bolts of why it is you should eat this and not that, or exercise like this and not that, then the more you will become invested in your own health. And not just the why, but how you respond to it. Learn to listen to your body. It takes time no doubt. But as Jamie argues in his piece, it will pay off. In the end you will have the information to make decisions for yourself and determine what works, what doesn't, and what you can and are willing to get away with. It's like a big puzzle. And if you consistently plug away at that puzzle and learn how the pieces fit together, you will be taking an enormous step toward your health freedom.
Consistency works for a lot of things in life: Investing, Career, Relationships. Its no different with learning how your body works. Consistently putting in a little time and effort will reap huge rewards in how you look, feel and perform. Your health is worth it.