4.
Limiting beliefs
The biggest things that gets in the way of us accomplishing our goals is ourselves. What we believe about ourselves ends up becoming true. If you think you are stupid and constantly tell yourself so then you will start to justify all the dumb things you do. On the flip side, if you tell yourself you are smart, you will start to look for all the things that justify your belief of being smart.
It's like when you have a crush on someone and you start to look for signs if they like you or not. Many times, if you have a high confidence level you will think the person likes you. If your confidence is low, the same person will give you the same signals but you might think that person doesn't like you. Both of these beliefs can change how you end up interacting with your crush.
If you believe something is possible and work hard towards it, there is a good chance you will achieve it. It will take time and hard work. It will take sweat and effort, but if you have the tools, work hard and believe in yourself, anything is possible.