Reconstructing the Voice

Recently I started to attempt to return to my natural voice. It has proven very difficult since I haven't used it for years. I changed it because of my last girlfriend. When ever she would sleep or rest with her head on my chest she would complain when I spoke since my natural voice resonates in my chest and causes a vibration. I also changed it because I wasn't a fan of being noticed and that voice carried well through a crowd or a quiet place. I find myself slipping back into the voice I have been using when I don't focus on my speech. I tried to switch back during one of my acting classes but I didn't want to sound ridiculous by switching back and forth while trying to ingrain my old voice pattern. Here is the perfect place because most of the people I am here with most likely will only see me in passing or even not at all once we return. I only have a few months to work on it so I will need to constantly keep my mind focused if I want to make any headway towards change.