Need help in building self confidence

Need help in building self confidence Like the title says, I need some serious advice on building self confidence . I used to be a confident person till high school but now all of a sudden I don't have any confidence in myself. I feel as though I am inferior to every new person I meet. I feel like I am not a capable person like others. Because of this my personality has shifted into becoming a pushover introverted boring guy. It's hard to see my friends being social and meeting new people when I have a tough time at just feeling confident about myself. The only time I feel a little confident is when I am in the gym, because you don't have to really talk while working out.