He said his first sexual encounter with another man didn't happen until he was 23.
"It used to be a very, very difficult and very shaming, 'disgusting' part of my life," he said. "It was incongruent with how I wanted to live and that was the hardest part."
Preston said a friend told him about the "Journey to Manhood" retreat three years ago and he decided to give it a try. He has been coming back ever since and praised the program for how it has helped him.
"It's been life changing. It's been a whole new take on life. It's been absolutely miraculous, for me personally," he said. "I feel some of the feelings or the attractions from time to time, you bet, that can be there. But I don't feel the compulsion anymore to have to pursue that."
Wyler's "People Can Change" program is built on the non-scientific premise that people can change their sexual orientation if they just "work" at it. It's part of the most recent wave of programs offering so-called "gay reparative therapy."
These approaches are not entirely new. Efforts to convert homosexuals to heterosexuals were widely accepted by the psychiatric community in the 1950s and '60s, when gays were often considered mentally ill. This idea is no longer accepted by the mainstream mental health community.
"The American Psychiatric Association's position since 1973, almost 40 years now, is that homosexuality is not a mental disorder. It is not something that requires psychological treatment," said Dr. Jack Drescher of the American Psychiatric Association.
According to Drescher, "change" therapy is not legitimate from a clinical standpoint and mental health professionals warn it can actually be harmful.
"People spend a lot of time and money on these treatments that don't work," he said. Among the risks he mentioned were people blaming themselves for ultimately being unable to change, as well as people being encouraged to enter unfulfilling heterosexual marriages that often end in disaster.
"So many people report that they feel depressed, suicidal, anxious, and hopeless, those are not uncommon responses to a failed treatment," he said.
"Journey into Manhood" is an intensive 48 hours of what Wyler calls "deep emotional work." In one exercise, the men are asked to confront their old identities.
Preston attached a label to his chest that read "gay" and then ripped it off to show that it was no longer a label he accepted. He attached a new label that read "father" to illustrate his new aspirations.
Wyler put on music to inspire the men as they wore their new labels. "You feel the strength of that man, you know who you are," he preached. "The shadow, it is still there, but it has shrunk in the daylight of the new day sun; the identities that you welcome and embrace, that lift you up and make you the best man you can be."
Such exercises are meant to build up a sense of "masculine" self-confidence.
Other activities include outdoor team-building exercises where the men are asked to walk blindfolded to teach them how to guide and trust one another. They are also asked to take a ride down a zip line attached to a 44-foot-tall tower as a way to learn how to confront their fears and "take a leap of faith."