Fitness/health and all goals in life are more of a mental game than the technical part of doing what it takes to reach those goals. The reason is because without the mental, you won't have the consistency to take the technical part of the goal to the max, in seeing that goal through.
Weight loss is an especially mental game. Let's start with a quick overview of why it's hard to lose weight. The human being was designed out of necessity of survival. If you didn't ever get hungry, you would die of starvation. So the hunger you experience causes you to want to find sources of energy that we know as food. This is one prime example of why the mental game is so important in achieving a weight loss goal.
Understanding we have this hunger sense, and learning the other things that work against us in weight loss, allows us to understand how to overcome these things and hit our goals, and that all starts in the mental.
Another example is dehydration. Our signal of dehydration sometimes mocks that of hunger, have you ever noticed you really shouldn't be hungry because you ate a little bit ago, but you are? You're probably dehydrated. Drinking a giant glass of water could make that feeling go away, and then you won't feel the need eat.
Building an understanding, and learning what inherently makes YOU tick, and learning how to accomplish your goals all starts in the mental! This is entirely a mind game, and you better get good at it.