Please help me

I am looking for a switch but i am so scared of getting rejected . I don't know why am i like this . I have seen my friend she's not scared of getting rejected she cracks the good company with the confidence and positivity. When my interviews gets scheduled i study so hard but at the time of the interview i will just not use my mind or just think "nhi hi hoga" so don't perform well. Please help me out . How to gain that confidence just like my friend.