I did this for the first time a few months ago and it was incredible. It made me more confident and especially during conversations where I'm able to hold someones gaze while talking. It's also quite powerful when you do this with a member of the opposite sex with a sly smile on your face. These days whenever I'm out I'll be scanning hungrily for anyone to make eye contact with me. I've had stare down battles with people on the tube, a game of first one to look away loses. Battles can last between 5-10 seconds.