Emotions are contagious. You know that guy at work that is always talking negatively and has a poor attitude? He has an effect on all of the people around him. This will naturally make a wake through the energies of life and make others think the same way; it is just the way things work in our mind.
If emotions are contagious, don't we want to spread good emotions? MAGNETIC emotions? Happiness, love, cheer, laughter, positivity, courage are all great emotions, but showing others you have confidence in yourself doesn't just boost how you feel about yourself, but how others will feel about you as well. Confidence is a part of being charismatic. This ties into what I have been talking about before with opportunity and mindset, and if you have confidence in yourself, it will be a part of that puzzle coming together to make your mind at ease. You are comfortable with yourself.