But the former All Blacks star was facing one of his toughest challenges this month - growing a moustache to raise awareness about mental health.
"I can't grow a strong mo' (moustache)," Carter, who normally only has to shave about twice a week, said on Thursday.
"I have done bits and pieces over the years but never committed to growing one for a month.
"It's been just over a week and it's pathetic really."
The 38-year-old's commitment to his "slug" is related to the global charity Movember, which focuses on men's health issues, although he was particularly interested in raising awareness of mental health and suicide among men.
Carter has started a social media campaign #keeptheballgoing where people will be encouraged to film themselves catching a ball and then 'passing it on' to three friends as a way of "checking in" on their mental health.
He added it was particularly important this year because the novel coronavirus pandemic had exacerbated people's anxiety around job security and their health.
"A man commits suicide every minute around the world," Carter said. "Three out of four suicides are men as well. So it's a serious issue.
"I knew it was bad. But I didn't realise until recently just how bad it was."
Carter said he knew people who had committed suicide and while he battled with his own ups and downs throughout his storied rugby career he was lucky enough to have support from family and friends.
He added the stigma around discussing mental health was also slowly diminishing, with former All Blacks winger John Kirwan instrumental in elevating the issue in normally stoic New Zealand's collective consciousness.
"He has been amazing," Carter said of Kirwan's revelation of his battles with depression and work to challenge attitudes towards it.
"The work he has done around men's mental health and mental health (in general) ... He is a real advocate for it and doing a great job."
Carter had also reached out to the current All Blacks, especially captain Sam Cane, to get the team involved.
Scrumhalf Brad Weber said during a video conference on Thursday that he was also participating in Movember although his efforts were not that prominent.
"It's nice to know that I'm not the only one growing a pathetic moustache," Carter said with a laugh.
"(But) you don't have to grow a moustache. It's more just an opportunity to reach out to a few mates and to check in and create awareness."