Think about it. What makes one qualified?
- Willingness to fail?
It's all of these, but it's also more than that. If you can get people to talk about your idea, think differently about something, change a habit, try something new, buy something, do something outside of their comfort zone, chances are you're more qualified than you think.
It's ironic, it's usually the people who think that they are the least qualified who are probably the most qualified out there. The opposite also seems to be true. Being humble makes you qualified.
Don't think that just because you are learning about something that doesn't make you qualified. Some of the best teachers are those who are in the beginning stages of their learning and development. They are passionate about what they do and that passion is contagious.
The opposite also seems to be true. Sometimes masters are awful teachers. Their arrogance can be blinding. What worked for them might not work for you.
So stop thinking you aren't qualified. If you want to teach something, teach it; write a book about something, write it; coach someone, coach them. As long as you are all in and dedicated to becoming an expert (and a master), and you put in the work, you are qualified.