There is a misconception that Voice Acting is just talking behind a microphone. While this is true to a degree, this is just scraping the surface. As the title describes, it is voice ACTING — acting with one's voice.
With voice acting, you have to make the listener feel what you are feeling, which also means that you should be feeling when you are delivering the lines. Unlike, on camera and stage acting, the audience does not get to see the struggle, the joy or any other emotion you are experiencing.
When getting into voice over it is important to have a passion to act.
You might say “But I don’t know how to act!” To that I say, you will!
Whether you have been acting for years or just getting started, the more you practice and hone your craft the better you will become. When I started my voice over journey, I was terrible at making what was written on paper, come to life and feel genuine and natural. Cold reading was something I struggled with. After hundreds of auditions and a handful of projects, I now feel comfortable reading a script and applying a natural emotion to it. It might be later down in the script that I might have selected the wrong emotion based on the scene, but I change that on the fly and adapt. Then when I read the lines again, I have a better understanding of what the character is feeling.
Sometimes you will find that there is not enough information to determine the scene. In this case, pick one and run with it. The important part is, do you believe what you are saying?