Great question. Why do you feel you do not have a good voice? How often do you listen to your voice? Are you using inflection, emotion, and energy when speaking?
You are going to be your worst critic when it comes to listening to your voice. What do others think about your voice?
As a previous radio DJ and now a successful voiceover artist, I have to listen to my voice all the time. It was not easy to listen to it at first. I too felt I had a bad voice.
My recommendation is to record your voice and wait a week to listen to it. It removes the emotion and you will have a different perspective when listening to it.