There has been talk of rugby's first truly global superstar making a comeback in France later this year and his involvement in bodybuilding has helped him get back into shape.
Lomu will enter Saturday's body building competition weighing 114kg; some 28kg less than when his struggles with his kidney disorder were at their worst.
"I just started out wanting to get back in shape and it's just gone from there," Lomu told the Dominion Post.
"I've always loved lifting weights - just ask the All Blacks - so it's been a lot of fun. I can't wait to get up there on Saturday.
"You do look in the mirror at your body and it's amazing how critical you become," added Lomu, who won 63 caps for New Zealand between 1994 and 2002.
"I'm seeing myself in a different shape. It's been hard work but anybody can be a bodybuilder. It's all about discipline."