Negative self-talk can plague even the most successful of people, and Jonny Wilkinson has shared how he’s learning to fight it.

“It’s amazing what comes out of me sometimes – very black and white, very conditional, very, very critical,” the England rugby legend admits. “We go about acting on behalf of this incredible voice in our mind, but if we stopped to ask, ‘Hold on, who are you?’ – there’s nothing there.

“We’re listening to the rantings of someone that we wouldn’t even be friends with. If you weren’t stuck inside my head – would we even be mates? Who listens to opinions and advice from people that clearly don’t have your best interests at heart?

“Pleasing [that voice] it is just enabling it,” Wilkinson, 43, adds. “But if you challenge it, it gets a bit nervous and jittery.”

Learning this, he says, has made a big different to his mental health, which he has opened up about struggling with since retiring in 2014.

The moment in Wilkinson’s illustrious Rugby Union career that stands out for most is drop-kicking England to World Cup victory, mere seconds before the end of the match against Australia in 2003. But even at the height of his athletic success, there was crippling self-doubt.

“My entire life was about avoiding humiliation: every loss, every defeat, every mistake, every kind of comment from someone about me, every report on the news – if it wasn’t how I wanted it, it was some form of humiliation.”

Wilkinson, who is joining England in a coaching role for the 2023 Rugby World Cup, doesn’t look back on his time playing professionally with any regrets, but says: “When I felt good about myself, my gift, my talent was channelled very, very effectively. I didn’t stand in the way of my ability.

“When I felt not so good about myself, I felt unworthy or undeserving, or insufficient or insecure… that is just standing in the way of your unique greatness. I’m not saying I was great – I’m talking about everyone,” he adds. “Operating through self-doubt is like saying, ‘I don’t want to see what I’m capable of.’ I spent a lot of my career feeling that way about myself.”

Now, a lot has shifted: “I have a very different relationship to shame and guilt. I just don’t really do it, whereas I used to be functioning mostly through it.”

The trick, he says, is to learn how to be a good teammate to yourself.

“What are the most phenomenal teammates around whom I feel incredible, and why? And it’s never because people are hanging around telling me what I should be doing. I never hang around people who are constantly competing with me or comparing me to others,” says the father-of-one. “Being the best teammate to myself is one of the most amazing things, [it’s about] compassion and patience.”

Talking openly about mental health has of course become more common in recent years, and Wilkinson is keen to stress that speaking up when you are struggling is a strength.

“It’s got nothing to do with weakness – it couldn’t be more the opposite of weakness,” he shares. “It’s saying, ‘I’m up against something that is huge for me’.”

These days, Wilkinson is taking a holistic approach to managing health. He has just launched a new line of kombuchas with his brand No.1 Living Plus, enriched with adaptogens (herbs and roots said to support the body with the way it responds to stress).

“Gut health is very, very much connected to all kinds of health,” he says. “It’s one component that is constantly responding and interacting with the rest of your body to create that kind of holistic functioning.

“And when you’re working well, in a connected, holistic way, life experience just goes up a level. You just wake up in the morning and you feel good about yourself. You feel good about the day ahead.”

At this time of year, many of us will be paying closer attention to our health, but Wilkinson is keen to show that good health goes far deeper than numbers on scales or weights on the end of a barbell.

“I’ve been massively driven by purely that physical level, what I could achieve physically, how many people might recognise my name, give me respect or confirmation – I felt I needed that kind of stuff,” he reflects.

He says he’s learned that what’s more important for him is “the exploration of who you are”, and diving into your passions and interests.

“In order to do that, it’s now or never,” he says. “I spent a lot of my life in this idea that I’m going to somehow find my ‘now’ in the future – it doesn’t work, that idea that ‘I’ll do that tomorrow’.

“January may as well be February, may as well be September – ultimately it’s what’s exciting to me now? What am I willing to really commit to?”

Right now it’s simply breathing through his nose – including during exercise (which sounds inordinately difficult). “Nasal breathing is incredible! I’m trying to focus more on doing that, to see how it affects my performance.”

To do it properly you need to be relaxed, he notes, so it helps him tackle stress throughout the day too.

“[It makes me] aware of whether I’m stressed,” he says. “All bets are off when you’re busy focusing on your day, being like, ‘Am I stressed? Do I need to be stressed? Is this a true feeling about this situation?'”

No.1 Living Plus is available at no1living.com and in Sainsburys and Holland and Barrett.