Being of one mind means avoiding duality, internal conflicts, divisiveness. One should seek completeness. It means saying what one means, and meaning what one says. It means not doing things one fears to admit. It means living one life.
Examples of one-mindedness:
One should not deceive others. One should not deceive self. One should be sincere in speech, and keep ones word.
One should eliminate internal dissonance. If one believes a way, one should behave that way. One should be the same person, always. This is not to discount the need for roles, but let us know the difference between what we do and who we are; and let them not conflict.
Secrets are heavy burdens; guilt is heavier, but secret guilt is more than we should bear. One should spare self of these burdens by simply not doing the things one would want to keep secret.