To be a voiceover you need to be mentally strong
Believe it or not, voice over requires you to be mentally strong. There are going to be a lot of times where you can feel unworthy or untalented due to the enormous amount of rejection that can be involved in voiceover. Don't let it get to you. The more you worry about winning the job, the more pressure you put on yourself during the audition process. Microphones are very sensitive and will pick up on desperation. Just remember if you have booked before, you are more than likely to book again!