Here is a single advice which could take you a long way:
Be specific!
Developing confidence is easy to do when focusing on a specific life situation.
Developing confidence has a lot to do with gaining knowledge, skills or expanded awareness in a specific field.
If you need to gain more confidence in your professional environment, try for instance getting extra experience or essential information.
If you need confidence for giving a public speech, you can put extra energy in your preparation. You could as well attend a seminar on communication skills.
If you need to gain confidence in social situations, taking extra care of your appearance, and buying a new trendy shirt could already be enough…
The point is that confidence has its roots in your being. It is more than an invisible “suspended” potential.
By developing confidence in a specific life situation, you will impact on your own mind, self esteem and confidence in general. You will progressively shift the way you perceive yourself.
Check with your coach to get focus, support and ideas with simple steps like these.