Sexton dreams of ultimate World Cup glory after grand slam
With his hair greying at the edges and the fact he will be 38 when the quadrennial showpiece gets underway in France in September, bowing out with a grand slam might seem a superb way to end his Test career.
However, though he said securing the grand slam with a 29-16 win over England at Lansdowne Road - in what was his 60th and final Six Nations appearance - was the high point of his career, he hopes "an even higher one" is to come.
Ireland have never got past the World Cup quarter-finals but are the world's number-one-ranked team and among the favourites.
Sexton found the 46-14 hammering by New Zealand in 2019 "hard to get over", but Andy Farrell's men will take some stopping in France.
"I think this grand slam is a part of the journey and very special," he said.
"Like the series in New Zealand was incredibly special (the Irish won a series there for the first time last year 2-1).
"We don't have to have a poor Six Nations to go on and win a World Cup, when England won in 2003 they had a grand slam in the same year, so we need to keep our feet on the ground first of all and keep building."
Sexton may not have been at his magisterial best against England - reflecting an error-strewn performance from his team-mates for the first 50 minutes - but a moment in the second half proved pivotal.
Pressed inside their 22 by England, who were just 10-9 down, he fluffed a clearance.
He then held his hands up and apologised to his team-mates but also waved his hands in the air to gee them and the crowd up.
Within minutes Sexton had righted the ship not only for himself, but also his team, with a sumptuous crossfield kick that eventually led to a try and eased the pressure.
'I'm not a dancer'
This was the sort of leadership quality that Farrell had seen in him while the Englishman was assistant to his predecessor Joe Schmidt.
It prompted him to name him captain after he took over as head coach following the 2019 World Cup.
Farrell made no bones about how deserving Sexton was to lift the trophy on Saturday.
"It's unbelievably fitting that in my opinion the greatest player ever to play for Ireland is able to sign off on a grand slam on St Patrick's Day, in front of his home crowd," said Farrell.
Sexton may be a hard taskmaster, although he is as tough on himself as his team-mates, but he is very much a team man.
He wanted to lift the trophy with another team-mate but Farrell told him he deserved to do it on his own.
The mutual respect - and in some cases friendship - between the captain and his players is palpable.
Veteran flanker Peter O'Mahony spoke of how Sexton had changed rugby for the better and made the team feel how it was to feel like a "proper Irishman".
Sexton - who celebrated the victory with his three children on the pitch - said that was probably a bit far-fetched.
Cian Healy has spoken of how the Sexton off the pitch, especially after a win, is "the most enjoyable Johnny to be around".
That Sexton was definitely going to be on show later on Saturday as even he said he would park analysis of the match for "48 hours" and enjoy himself.
However, whether he will be dancing is another matter as a dance move that went awry when he converted Ireland's third try drew much merriment.
"I'm not a dancer, I can confirm that," said Sexton.
Farrell responded: "You will be tonight."