You don’t.
It’s like asking “how do you make fries and play football while diving?“
Makes no sense.
They’re 2 different things that don’t take off from each other, so there’s nothing to “balance”.
Authenticity has to do with how you bring your POV in a consistent manner. How you keep true to your beliefs (values).
Sales, with how you guide and bring your prospects to make an informed decision —being that decision in their best interest and not necessarily you.
Selling is leading. And to lead, you can bring your authenticity along the way.
Nothing to balance. Everything to leverage on each other.