"You have to interpret a long time to be able to interpret like yourself". Let's explore if and how interpreters develop skills and - eventually - their own style. I don't mean mannerisms or extroverty, but a good and natural, self-assured interpreting style.
The Ira Glass comment on how you know that what you do is not quite where you want it to be also applies to budding interpreters: you know what it should sound like, but you cannot quite get there yet. That is not only a question of skill, but also a question of routine and experience.
Personally, I strive for natural, even-paced delivery with good German and not too many unnecessary anglicisms. What about you? When do you know you did a good job at the end of the day?