To alter belief system, we must first acknowledge our limiting belief then we have to provide opposite thoughts, feelings and behavior to dispute that belief.
like if I belief I wouldn't get that so to tackle it I would do 3 things
alternative thought: I am getting that
alternative feeling: imagining I have get that
alternative behavior: I would do action to achieve that goal.
and have to remind our mind again and again with success stories, with feeling of getting that thing so that it start accepting as reality.
Aa our beliefs are former by almost 20 or + years of lifespan, of course it wouldn't change over a night but by constantly providing evidence against our limiting belief could help.