I consider labels to be a tool. They can be useful or dangerous. It depends who is wielding them.
As I often say, consistency is a powerful part of persuasion. It’s possible to shake yourself out of it, but you might need to ask someone who knows how if you can’t do it on your own.
For example, if you think of yourself as a stupid person and adopt the label into your identity, you will be more likely to consider simple mistakes as evidence of your own stupidity. In the future, you might feel embarrassed or dislike someone for voicing a better idea at the time, even if they make the same mistakes you do when you aren’t looking. Noticing yourself do something that seems smart might even make you feel bad because it clashes with the idea that you are a stupid person who makes bad decisions.
It also affects how you view other people. Suppose you label someone as trustworthy. Because the label was your idea, all of their future actions will be colored by the notion of trust. You might let them get away with things others wouldn’t because you trust them.
The heart of this is cognitive dissonance. If you set yourself a belief that a family member is hard working, and later see them lazily watching television while chores are unfinished, you might give them a pass. The alternative is admitting you made a poor judge of character. No one likes being wrong.
If you never focus your attention on whether or not they possess a certain character trait (e.g. honest, helpful, defensive, cool), you’ll probably never have a conscious opinion on whether they possess it. If you see a person who you previously labeled as “selfish” give money to a homeless person, you might be surprised that you misjudged them. But that surprise would be impossible if you had never given them that label. It seems obvious when I say it, but it’s true.
Use this to your advantage by labeling people and activities appropriately. Want to stop watching TV? Label it a “waste” and explain to yourself why. Make a small list of the ways it is painful to watch TV, and enjoyable to do a more productive activity. Need to help a friend improve their self-image? Ask them what is their best characteristic, agree with them (provided they give you a positive answer), and then ask how they know that. Get some reasons out of them so they dig into the position. You’ll have helped them become a better person and feel good that you helped someone else.