People often act contradictory to their own stated and intended goals.
For the next few days I'll look at a number of these ways of stopping your own progress.
#1: Contradictory Goals. This one is pretty common, in my experience. It might be the most common if you go by forum posts. You basically choose two or more things you want to do that aren't especially compatible with each other. They may be diametrically opposed ("I want to gain size and lose weight") or just hard to do at the same time ("I want to increase my strength as much as possible and lower my 5k time as much as possible without sacrificing either quality") but they're not easy to do at the same time. You end up chasing two rabbits running in different directions and that's not an easy way to catch either of them.
Other examples of this are: "I want to gain muscle, get bigger, and lose fat."
It's not that you can't gain muscle and lose fat at the same time, but it's always easier to chase one goal at a time. Another good example is wanting to gain muscle but not wanting to gain weight. You get this from weight-class athletes and weight-loss clients too focused on the scale and not the mirror, amongst others. Your goal - increased muscle size - should result in heavier weight for the same size because muscle tissue is more dense. The scale weight might even go up, even as you slim down and look better. But you've set two goals that end up affecting that measurement differently. It's like guys who want to gain some size and weight but are afraid to lose their "six pack" abs. It's extremely hard to convince your body to grow in size and stay extremely lean at the same time.
How about this one? "I want to tone up, but I don't want to gain any muscle." Right, you want sleek muscles but don't want any muscles. This one is really common because it's not clear to people that "toning" involves reducing body fat while increasing muscle tissue size and tension.
If these sound like you, your first task is to sit down and decide what those goals mean - and to settle on which one is more important and prioritize it, or dump one or the other entirely.