Before you can expect anyone else to understand your ability and what you can offer, you must know this about yourself. This isn’t something you can just conjure up as employers and people in general will be able to see right through any qualities that aren’t genuine.
Do some self-reflection. Understand what makes you who you are. What makes you get up each morning? What makes you joyful? What makes you angry? What do you strive to leave behind when you leave this world?
Understanding what you can bring to a position and why you are such an asset will make it clear to people around you. Believe in yourself first.