How do you think that well-known experts became recognized as experts? They focused on something that was interesting to them; they mastered the literature; and they develop their own experience so that they could make their own contribution. The result is a self-reinforcing process. The more you see, the greater the experience and expertise, the more you see.

How to Be an Expert in One Easy Lesson Milton Packer shares his advice for earning recognition as an authority

I know how to take it off and keep it off.

Two. Hundred. Pounds.  I’ve kept the weight off for over forty years.

This makes me an expert.