Byrne, 50, from Dublin, has postponed her job while she is in "X-Factor" camp to train for live shows.
Byrne won the hearts of the judges on the British reality show during her auditions a few weeks ago.
"I'm enjoying every minute of it, and I have more to give, believe me," Byrne told the Herald newspaper.
"I am living a dream and I can't believe it. It is a fantastic experience.
"I knew I could sing from around the age of nine, when my brother got a reel-to-reel tape recorder and recorded me singing Dana.
"She had just won the Eurovision at the time.
She continued, "You could even hear the cat joining in half way through.
"But I didn't really have any idea about the power of my voice until now, when I started "X Factor", and I'm getting a great reaction.
"To be honest I don't think I would have had the courage to enter years ago.
"It's only in the last while, going through the change in life, when my body changed, and my hormones changed, that I grew stronger as a woman. I only got the confidence with that happening, and seeing Susan Boyle and how she did so well, that gave me the drive to go forward,.
"I realized that I was getting older, and that it was a case of now or never.
"I was afraid that I'd wake up some day when I was 60 and regret not going for it."
Byrne said to date her experience on the show has been nothing but positive.
"Simon is a gentleman; he is a really nice man," she said.
"They are all just people like you and me at the end of the day."
Asked if she had ambitions to win "X Factor," Mary said she guessed all the performers would dream of winning it.
"I don't know if I will win it. I doubt it. But I would love to do some live shows, I hope I get that far," Mary told the Herald.
"But my ultimate dream is to walk into Tesco, where I work, and see my album on the shelf.
"That would be the ultimate dream, to record an album and see people buying it."
The Herald asked Mary how she felt when she was on stage, performing to an audience.
"It's like a different person takes over me.
"I become another person, it's very hard to explain," Mary smiled.
"Then when I get off the stage I become Mary Byrne again, loving a laugh and a joke."