Zschech started on television at the age of 10, as part of an Australian children's show, Happy Go Round. When she was 13, her parents divorced and the emotional stress of being on television and her parents' divorce resulted in her having bulimia for about four years.
In 1980, when Zschech was 15, her father rededicated his life to Christ and began taking her to church, where she also became a committed Christian and met her future husband, Mark Zschech. When they married, her husband suggested that they move from Brisbane to Sydney, which was confirmed at a small church they were visiting one Sunday when the guest speaker said in the middle of his sermon, "This doesn't happen to me very often, but whatever it is you two prayed last night, God says do it now." They began attending Hills Christian Life Centre, which would become Hillsong Church.
On 11 December 2013, Zschech was diagnosed with breast cancer. In a blog dated 30 November 2014, she wrote that she has been healed of cancer, which her doctor termed "quite miraculous".