A common way that lots of people adopt in the process of building their lives revolves around the principle of lack and scarcity. Their mindset is that there is simply never enough to go around. The problem is that this belief then becomes a self fulfilling prophecy which cause the person to act and behave in such a way that life becomes a struggle and they live in a reality where it's hard to make ends meet.
Interestingly, abundance and scarcity are both a matter of perception.
So once you decide to change your perception, you feelings will change and your actions and behaviours will reflect the perception you hold as being true for you. Whatever you believe, whatever you look for - you will find.