Everyone hates to fail, but for some people, failing presents such a significant psychological threat their motivation to avoid failure exceeds their motivation to succeed. This fear of failure causes them to unconsciously sabotage their chances of success, in a variety of ways.
Avoid giving yourself time to make excuses. When you see a hot girl, don't make excuses like 'she's probably in a relationship', 'she is on her phone', 'she is jogging', or 'man, I look so bad'. Believe it that there is no valid excuse to not talk to her. At worst she would say 'no' and walk away. You have to try again and again to get good at this.