The 30-year-old former Hurricanes midfielder has also admitted observing ex-All Black Ma'a Nonu's professionalism gave his career a boost, culminating in his success in Wales since signing for the Cardiff Blues.
Halaholo helped Wales score a 25-24 Six Nations win over Scotland in Edinburgh on Sunday, highlighted by a superbly-timed pass for Louis Rees-Zammit's match-winning final try.
The Aucklander was only called into Wales' camp three days before the game after a midfield injury crisis, and was delighted to get his first cap after a serious knee injury cost him a call-up last year.
"I want to thank everyone that has sent me a message of support I’m sorry I cannot get to everyone as it has been a lot, but I’m truly grateful and Thankful for your messages of support for me and my family,'' Halaholo said on social media.
"Thank you to everyone that has been part of the journey in getting me this first cap. Lastly just want to thank the management and all the boys in the team today for making me feel so welcome, and I’m truly honoured to be part of this team.
"Awesome to get the win and although I have plenty to work on I’m looking forward to contributing as much as I can to this team. Much love, Willis."
Playing at Murrayfield is a far cry from the life Halaholo was leading in Auckland a decade ago when his weight ballooned to 115kg from a diet of booze and takeaways.
“I had got into bad habits. There was a huge drinking culture around then,'' Halaholo told Wales Online last week, revealing he was "out on the town with the boys'' the night his wife went into labour.
“I wasn’t getting involved enough on the field because I was so overweight and unfit.”
Halaholo was living with wife Sandra and infant daughter Atu in his in-laws' west Auckland garage when “one night I decided to just give it all up [the booze and gang culture] and give rugby a real crack.
“My daughter was the strong motivation to give everything up and give rugby another go.
A move to Southland got his career back on track in 2013.
After rediscovering his fitness, Halaholo went on to star for the Stags in the NPC, and, in 2015, he earned a Super Rugby contract with the Hurricanes where he had the locker next to Nonu's.
“I learned a lot about myself from him, too... His professionalism, recovery, nutrition... everything was so important to him,'' Halaholo told Wales Online.
“I thought you could cheat a little bit, but no, he was on the money every time - ice baths and everything.''
Halahalo went on to be the starting second five-eighth in their 2016 Super Rugby final win over the Lions before signing later that year for Cardiff, where two of his four children have been born.
Reflecting on his journey from promising Auckland academy prospect to the Six Nations area, he told Wales Online: “I’ve learned lots of life lessons, having gotten involved with gangs and stuff in the past.”
Now, family is his main motivation, with Halaholo crediting his parents, who migrated to Auckland from Tonga, for teaching him “to work hard, so that I can get a better life for my kids, like they did for me.’’