But after shedding almost 20 kilograms in the pre-season, Auelua says his new Brumbies leadership role will drive him to reach his goal of representing the Wallabies.

A shoulder injury last year cost him a Wallabies debut in the British and Irish Lions series, triggering a turbulent off-season for 29-year-old Auelua.

Missing a Wallabies spot, losing the Super Rugby final and having the first serious operation of his career led to Auelua slipping into a mindset he describes as post-surgery depression.

''Mentally I fell into a slump, the drive wasn't there and I started to doubt myself,'' Auelua said.

''I told the guys I wasn't happy, I was all over the shop. It wasn't just rugby, it was a chain reaction and I lost my way.

''I'm so grateful pre-season started when it did … I had post-surgery depression.

''But a guy like David Pocock pushed me, he motivated me, the medical staff got me back and now I'm lifting weights that I wasn't even doing last year.''

Auelua injured his shoulder in a match against the Wellington Hurricanes in May last year.

Not long after getting off the field, then Wallabies coach Robbie Deans called former Brumbies mentor Jake White to tell him Auelua was in the Test squad for the historic series against the Lions.

''It was devastating … I based my return to Australia [in 2012] about being a part of that series and I wasn't a part of it. I dwelt on it and it brought me down,'' Auelua said.

''Jake told him [Deans] my shoulder was gone. We found out it was a full dislocation - that was a battle for me.''

The powerhouse forward shocked Brumbies staff when he reported for pre-season about 20 kilograms above his playing weight. But a training stint with ex-Wallabies captain Pocock reinvigorated Auelua's motivation.

Auelua has trimmed down to 121 kilograms and is targeting Wallabies redemption this year.

He was added to a six-man Brumbies leadership group earlier this week, joining captain Ben Mowen, Stephen Moore, Pocock, Christian Lealiifano and senior back Clyde Rathbone.

Brumbies director of rugby Laurie Fisher said Auelua's actions would speak louder than words.

''It will force him to train hard. We don't want 'Fots' telling people what to do, we want him to show them,'' Fisher said.

''He's a great trainer and a wonderful example of training at 100 per cent. That's what we want from him.''

Coach Stephen Larkham said: ''Fotu didn't go on a fad diet. He went from 140 kilograms back to 121 kilograms, and he continually worked for it.

''He's training with immense intensity and effort now, he really leads by example on the field.''

Auelua returned to Australia for the 2012 Super Rugby season after starting his career abroad.

Auelua, a schoolboy star, admits he wasted his chances as a junior and feared his Super Rugby and Test hopes were dashed when he started playing in France.

Auelua's goal is to earn a place in the Brumbies' starting XV after spending most of last season as an impact player.

''I'm grateful to be part of the leadership group, it forces me to work hard and I don't want to let anyone down,'' Auelua said.

''[Pocock] has been a massive influence on me this pre-season; it's a testament to who he is as a player. It's about what you do on the field, not what you say.''