Fall means harvest time. But for Ethan Zohn, it's a harvest of a whole different kind.
"Today is a nice fall day outside, which means it's a perfect day to harvest your stem cells," Zohn, 35, says in his latest video diary.
Dressed in a hoodie and lying in a hospital bed where he is connected to a series of tubes, Zohn explains how doctors are taking stem cells from his own blood now to save for later use – when he undergoes a full stem-cell transplant to stave off his resurgent cancer.
In late August, after giving the Survivor: Africa winner three months of intense chemotherapy, Zohn's doctors discovered that the Hodgkin's lymphoma Zohn had been fighting since spring had spread. He began new rounds of chemo in September, and is expected to undergo weeks of radiation therapy before undergoing the transplant.
"What happens is they take the blood out of this arm, it goes up through these tubes and over to that weird, Star Trek, 1950s console," he points out in the video, showing off a centrifuge machine that's separating the stem cells from his blood as he lies there. "Then it's put back into my body through this arm."
The entire stem-cell harvest took about three hours. The stem-cell transplant will require a hospital stay of a full month, as doctors attempt to re-build Zohn's red and white blood cell count from scratch – and render him cancer-free.
For more on Ethan Zohn's fight against cancer, keep checking back to PEOPLE.com