A sense of not belonging especially to those who matter to us destroys our Confidence utterly because it is the reaction of others which moulds, confirms and maintain our Self Image. Most juvenile and adult problems are caused by a deep sense of not belonging to anyone or anything. Other people's attention, recognition, praise, affection and love are life lines to your endeavours reinforcing who you are and giving you the reason to continue in your life. Self Esteem is the opinion you have of yourselves. With no Confidence and Low Self Esteem you appear either negative to other people or friendly to mask your feelings of inadequacy.
Confidence has to do lots with our relationships with other people.
You don't want to feel inferior to anyone. When you go to work you want to fulfill your potential. You don't want to be bullied by your workmates or superiors. You want to contribute as much as you can. A smile is the magnet that can change the response of other people around you.