Zohn, 41, is engaged to New York City interior designer Lisa Heywood, 47, the couple tell PEOPLE exclusively.
"This is the reason I survived cancer twice ... to meet Lisa and start a beautiful and healthy new life together," says Zohn, who was first diagnosed with Hodgkin's lymphoma in 2009 but is now cancer-free after receiving a stem-cell transplant from his brother in 2013.
The former soccer player and Heywood dated for two years after meeting at a Clinton Global Initiative charity event. Zohn, who competed in Survivor: Africa, Survivor: All Stars and The Amazing Race, proposed to his fiancée on the dock of their new lake house in New Hampshire.
Heywood's new bling holds a special significance: Zohn's father died from cancer when he was just 14 years old, and he popped the question with the diamond his dad gave his mother – along with a new setting that Zohn designed himself.
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Reporting by JULIE JORDAN