How can you develop self-confidence?

 Ability and self-confidence are a loop. Recall your abilities or start following your passions and excelling at them, which will increase your self-confidence. Once you achieve it in one field, you are more likely to try other fields too. If you know the King Bruce and spider story, the spider keeps trying even though it fails. Trials are a given. Finding your own way of succeeding is the joy. Nothing ventured nothing gained.