No one lacks confidence. Confidence is the inherent belief that you can rely on something. We can have confidence in others, confidence in a task, and confidence in ourselves. It's an internal thing based on an unwavering belief.
The reason I say that no one lacks it is because we all have confidence in some capacity. We do, really. It's just that we don't always realise it.
Imagine if you will, meeting a person at a social gathering. You get talking and this person tells you that in their life they have accomplished many things. They have a great list of 'positives'- things of which they can be proud - but in their negative column they put a lack of confidence. They tell you that it is the one thing they just don't have and that they are at a loss because, despite being skilled in so many ways, this feels like the greatest failure.
Confidence comes in many forms. In this person's case they are referring to a lack of social confidence. What they mean when they say they don't have confidence is that they don't feel sure enough of themselves in social situations to approach strangers and strike up a conversation.
A lack of confidence when it comes to approaching strangers is not an inherent lack of any confidence at all. For example, suppose this person has a successful career in which they have performed extremely well. They studied for a long time and have worked in many different roles in their industry, gaining success and rising to a place where they are respected for their talents. They were confident in the skills they gained from their education. They were confident in the knowledge they have of their chosen field. They were confident in their abilities as a professional to build a successful career.
It's simply because of a belief that confidence is confined to a specific situation that this individual feels they lack it.
Often times we are not aware of these sorts of limiting beliefs. Because we are told that confidence has something to do with bravery or with social performance, we are not aware of the great level of self belief we have in other areas.
A great way to let go of this limitation is to sit down and write a list of the things which you know you are good at. Anything at all, be it cooking, drawing, gardening, pet care, reading, athletics, teaching, listening - you get the idea. Belief in your ability to do something is confidence.
We can't be confident in all things. For example, I don't believe I'd ever be good at treating traumatic injury. Beyond being able to budget, I have very little faith in my math skills. I don't feel very assured in my ability to learn new languages. There are so many other examples, but I don't have to be confident in everything and nor does anyone else. When we encounter something where we feel we just don't believe in ourselves, it helps to remember our list of the things we are confident in.
Remember, confidence is something that comes from within. It's our capacity to recognise our own strengths without need of external approval. When we recognise where we are strongest, where we have unwavering faith in our ability to do something, we are reminded that oftentimes these things were things we learned over time. When we encounter a time where we don't feel so sure, we can use our confidence in a different area to remind us of our ability to grow.