One of the most important things in life is CONFIDENCE. Everything else follows it. Having faced a very low confidence in myself, I have realised the value of it even more. The first thing we as adults need to instill in children is confidence. Rest of the things come as a result of confidence. Again, there is a line between overconfidence and being just confident.
Also this confidence level keeps varying at various stages of one's life. I am not sure if it can be a straight line for anyone throughout life. It goes up and down due to various factors. The key is to keep the confidence level stable and higher up to sail through this journey. As I mentioned earlier, I have struggled with being confident. I have felt low on this most of the time and after all these years, I have started focusing on improving this. There is no one way to boost our confidence. But definitely doing things we love and enjoy is one big and easy way.
After a few years of feeling physically low on energy, I was feeling that I have become weak physically. It is very easy for one to feel low on confidence as so many external factors also act as boosters. But slowly I have started relying on all the things I enjoy doing and have started doing more of those and without realizing my confidence level has been increasing. It is a very tough feeling to explain in words. I can only say that anyone who feels confident knows the joy of feeling confident. The best part is, it being very infectious. When we feel confident about one thing, we slowly start feeling confident in all other aspects of life as well. Gradually it spreads like a wildfire 
Remember, confidence does not mean perfection or coming first.
It just enables us to enjoy everything we do. It tells us that it is ok to have doubts, and yet continue, tells us it is ok if we don't get answers, but to continue walking, tells us to see the beauty in uncertainty. And so many other things.
I was super hungry after one of my classes, and so I went to a hotel and ate breakfast alone. My mom was surprised and asked if I didn't feel odd eating alone. And I feel inspired seeing her do everything alone. So, for each one of us this confidence-booster will be different. For one it may be doing something that one is not comfortable with; for someone it may be doing something they are very good at; for someone doing something that they are scared of; for someone it could be doing something that one is not good at, but just that trying can boost the confidence; and for someone it can be doing something new, trying new things; doing things alone; doing things with a new person - the list varies with each individual and for the same individual it could change with time/circumstance. Key is to identify our confidence-booster and consistently do the same.
My easy go-to confidence booster
