When you have actual abundance you automatically have abundance mentality. It's as automatic as breathing and requires no effort. It simply is the state you exist in.
Getting the mentality first in order to get ACTUAL abundance requires getting over yourself & requires that you STOP caring one iota what anybody else thinks.
It's also habit driven as success in anything is. Get into the habit of social interaction with those around you at all times. By doing this you learn social calibration and overcome fear.
Fear is what drives all scarcity thinking. Fear of rejection, fear of looking stupid, fear of what others think or say....fear fear and more fear.
They are ALL imaginary fears. Change your fundamental thinking, habituate yourself to the change, and your results WILL be different.