"It was all encompassing. I was living in the heart of Tel Aviv, doing PR, mingling, meeting the right people, going to all the parties, wearing the right clothes.
"It was fun but very soon I felt disconnected from it, emotionally and socially. So I started an unbelievably intense search.
"For about 10 months I would read books and meet religious leaders wherever I was appearing. It was a type of obsession."
Avichai, who told his story at Whitefield Synagogue in Manchester last week, said he had "no connection to religion" as a young man, even though his British-born parents were modern Orthodox.
Eventually, when he was modelling, he met a Buddhist guru who gave him the "shock of his life. I told him that I was searching for a spiritual system where faith and intellect could happily co-exist, and he said that the only religion that fitted the bill was Judaism.
"I was flabbergasted. Judaism was the last place I thought I would find answers. I thought I already knew everything there was to know about it.
"As a young man, living a religious life in a technical way, without constant spiritual rejuvenation, produced an emotional vacuum for me. I wasn't aware of it as a child, but it drove me to seek excitement elsewhere."
At 18, Cohen joined the army's elite Duvdevan commando unit, working his way through the ranks to become a commander. But it was during a break in his fifth year of service that he was spotted by modelling scouts at a Tel Aviv gym. Within two weeks he was on the catwalks of the UK, Italy and Germany.
His chiselled chin, blue eyes and 6ft 1in frame appeared in campaigns for the likes of Gianfranco Ferre, Levi's and
Armani.
After completing a campaign for Polgat, the Israeli men's fashion company, he surprised the fashion world by giving away his designer clothes and disappearing from the public gaze. "At first I kept Shabbat for two to three hours. It was careful and deliberate. Even if I didn't necessarily feel the spiritual connection, I did it, like a soldier - because I knew it was the truth."
Eight months later he married a girl he had met when he was 14 in Kfar Haro'eh. She was four years older and doing her national service there.
Now a father of nine, Rabbi Cohen works for Zohar, a Belz organisation which aims to bring secular and religious Jews closer to Judaism. When asked about his transition from modern Orthodox to Chasid, he said: "There are wonderful people in both communities. It's just a matter of being complete. Like in a marriage - you can get along just fine, or you can have an unbelievable connection - that's how it is with God.
"People tend to confuse 'thorough' and 'extreme'. The Torah does not like extremes. It's as if you might say: 'What an extreme soldier! He wears his uniform all ironed and proper, he's always on time' - that's not extreme, that's just a good soldier.
"I pray to the Lord every day that I still have the fire to search for the truth as I did. It was a magnificent joy."
