Three things affects and/or contributes to a man's belief (and in turn form the bases of his mindset).
The people around: those you live with, engage with mostly, listen to and watch. E.g family members, friends, favourite celebs, mentors,etc.
The environment: the kind of people in an environment,what they do, the kind of passion, drive, desire, dreams, goals, types and levels of achievements they portray or have will affect the types of goals, desires, passion you will also have.
You: what you allow, accept and believe. You are the core determinant of your outcome. An example is, no one can force you to like a fair skin lady or guy, no matter how much you've heard about them, you alone can decide to consider whatever you've heard and conclude that oh yeah I now like fair skin ladies or guys.
Environment does a really crazy thing on us, it can determine how much and far you can dream, imagine. An environment can define a man's limitation, you barely can see beyond where you are. In fact, environment is still affects the other two (the people around you and yourself). A percentage of ourself is a product of what we heard from and saw our parents do, what we saw our neighbors, teachers, friends do and say. Well, I am pretty sure you have many things that you later debunked as you grew older in age and wisdom.
If not for internet exposure, I would probably still be settling for less. I grew up being comfortable with the same level everyone is at, no one is really aiming higher in any aspect: just be okay and manage, no struggle to get far and beyond the usual. I used to believe in settling for normal, being okay with the usual. Money for example, can you imagine being okay with earning just #5000 above everyone else who is earning let's say #10,000 and so satisfied with that. What I am saying is if a certain people in a community uses cars that are 10, 15 years behind and are cool with it. Automatically, I just believe and want that kind of car, max is that I would go one that is a year ahead of everyone.
I grew up among people who would fight anything beyond the usual that they know, their exposure. They talk down and bad concerning anything that's not what are used to, till you also feel bad for trying to do way better. The limitations of mind by the influence of environment.
I got my first few exposure when some of my older neighbors and family friends and church members went to University . They had changed a lot when they came home for holiday, talk, dress way better. It seemed like they came from an entirely different place: obviously, yes, university is another place because they were no longer confined to the areas of our small communities. Then, the internet did it own on me. Made me feel like I was 10, 20, 30 years behind in many things. I started to develop new passion and desires for things, I saw things online that improved or totally changed my taste and wants. By that time, I was already fighting my parents subtly to let me go out more (though being an introvert did it thing on me plenty times). Gradually I got better, I was sounding different from my peers at home. I was either too complex for them or too rude or too proud to them, well, I was apathetic to those things. I just wanted to get better and be like what I have been seeing on the internet.
Now, I even believe more in going out to places, getting exposed to new things, how people do things differently: and being inquisitive about how they are getting the results they are have, the books they read, their lifestyle and principles as a faster way to change my beliefs and mindset.
Another thing I used to believe but not anymore......
The unbalanced belief or truth of my religion. Nah, the fault is not the religion, it was the believers misinterpretations or choice to believe a part and neglect the other part maybe because one appeal the human way better (flesh if you know what I mean). The issue was I grew up to believe that I should leave everything to God, in the sense that I don't have to do so much. This particular belief made men to think that they don't have a part to play in their individual destiny: made them forget that there is God's part to play and then, an individual's part to play. Yes God will bless you, protect you, provide for you, heal you, but you have a part to play in all of this.
I will say I had suffered a lot before I realised that I was wrong. That belief made so many people mediocre in various aspects of their lives. Now, I get annoyed or irritated when I see those with that kinda mindset or find myself being a mediocre at any point. It is way easier to be lazy, neglecting your part and hoping on God but in end nothing will come because God won't do my part, your part for you. (For those who believe in God). Maybe I could have been richer, more knowledgeable, wiser and more valuable if I found out earlier.