He shared his heartache when his sister Connie was diagnosed with terminal cancer with Australia, putting his life on hold to cycle 15,995km across the country to raise millions for the cancer charity they set up together.
And Samuel Johnson, who first found fame on The Secret Life Of Us, only agreed to go on Ten's Dancing With The Stars to raise even more money for their charity, Love Your Sister.
But last week he broke ranks to urge fans to boycott voting on the finale, claiming that none of the money raised through the SMS voting system goes to charity.
Previously, when DWTS aired on Seven, a percentage of the phone votes went to the contestant's chosen charity.
"Being that SMS votes cost 55c and NONE of the proceeds go to charity, I'm asking that you forget voting for me and consider donating 55c to cancer research instead?," Sam posted on the Love Your Sister website.
"I've even created a special 55c button! Unforch it's not deductible, because it's less than two bucks. I cannot work harder for your donation and appreciate your consideration regardless."
Samuel, 41, is dancing for the mirrorball trophy – and the $50,000 first prize that does go to the winner's charity – in this week's grand finale against mummy blogger Constance Hall and drag queen Courtney Act.
But it's clear he believed that at least a percentage of the 55 cents his fans spent each time they voted for him would benefit Love Your Sister, which is why he urged fans to donate to the charity instead of voting for him.
And it is Connie and their charity that remains his biggest focus – even if it costs him the mirrorball, with Sam acknowledging that the intense training he's put in each week to stay in the competition involved "complete commitment and sacrifice."
Samuel started breast cancer charity Love Your Sister with Connie in 2012, organising fundraising drives around the nation, before his sister sadly lost her third battle with breast cancer in September 2017, leaving behind her two sons, Willoughby, 12, and Hamilton, 11.
Their charity has raised more than $9 million, with Sam in striking distance of fulfilling Connie's cherished dream of raising $10 million for cancer research.
"Life moves on, but as chief custodian of her legacy, she is still a part of everything I do," he says.
"It still feels weird to be doing this on my own still. But I no longer harbour the fears that I might fail without her. I've realised I can do this."
If Samuel wins Dancing With The Stars, Love Your Sister will receive the $50,000 winner's cheque, with Ten last week insisting the 55 cent voting fee merely covers the cost of the SMS voting service provided by a third party, and that the network does not profit from it.
The reaction from fans to his extraordinary call to boycott the SMS voting system was mixed, with some saying he should have investigated and found out about this before signing onto the series, while others praised his commitment to his beloved charity.
"Good on him for being honest even if he doesn't win he's keeping the cause going a great tribute to his sister," wrote one fan. "I honestly thought some or all went to their charities," posted another.
Others questioned why he wouldn't fight for the $50,000 winner's cheque donation. "I thought all charities would be grateful for that," wrote another fan.
Whether he wins or not, Samuel has undoubtedly helped Love Your Sister with his emotional performances, one of which he devoted to Connie, saying 2017 was his most memorable year because it was the one he lost her.
"She left this extraordinary legacy for the country," he said, fighting back tears, after the performance.
"It's not the cancer that's making me cry, it's all she did for me. The biggest thing she taught me is that now is awesome and to insist on joy."
To help "cancer vanquisher" Sam find a cure for cancer, visit loveyoursister.org