Do you have a voice problem? I do get calls and emails from time to time from prospective clients who tell me that they are absolutely certain that they have a voice problem. I then listen to a video that they send to me and my conclusion is typically that they do not have a voice problem.
What is a problem is getting tense and nervous and therefore, they start to talk like a machine. They sound monotone and robotic in the video but when I talk to them on the phone, that is not how they sound. In my mind, it is not your voice that is the problem. The problem is that they get nervous and they are changing themselves which is altering their voice.
The real problem here is to be careful about the self diagnosis which is quite often wrong. If you want to check, put your recorder on yourself, forget about it for a couple of hours, come back to it, and listen to your voice or get other people to listen to it and just ask them what they notice.
What you want in your voice is ups and downs and fast and slow and loud and soft parts as well as pausing at appropriate places. If you have this, then your voice is fine. It is not what is holding you back. The far bigger problem for most people is having something interesting to say. That is what your primary focus should be.