The sports-mad dad and husband who died suddenly in Cambodia on Monday had all of his young son's life to look forward to, says a grief-stricken friend.

Nick Hazlett, 46, died in a Phnom Penh hotel on May 18, while visiting Cambodia on a boys' trip. His friends found him unresponsive when they tried to rouse him from a nap.

Cambodian police believe Hazlett died of a heart attack in his sleep. That's come as a huge shock, close friend Shane Binnie said.

"He was extremely young at heart, fit and healthy and worked out a lot. He looked after