The biggest roadblock keeping you from your goals is that nagging feeling in the back of your head saying, "I might fail."
Completing the Stranger Challenge subjects you to failure and rejection. You learn to stop letting that fear hold you back.
I was actually surprised that I got rejected three times, but I at least but a smile one a few people's face and gave them a story for the day. Also, the guy who did accept got a lot of laughs from his friends :).