Any chance of Ireland's newest captain growing too big for his boots was quickly wiped away by his father, a former Shannon player, on hearing of his son's news.
"The first thing he said to me: 'congratulations on your captaincy! But, I am a colonel, so I pull rank,'" said Heaslip. His father is a retired high-ranking Irish army officer.
"They were literally his first words. I was put back in my box then. Dad has obviously led men in much more dangerous fields than me. Well, actually, I don't know," thought Heaslip, suddenly realising the brutes that patrol his working environment.
"He has led. He has never sat me down and told me how. But, probably how I learned rugby from my brothers was 'monkey-see, monkey-do'.
"Being around my father for so long and seeing him working in places like Kosovo, Cyprus, Israel, Belgium - you know, living over there - I obviously picked up a couple of things.
"It is probably why I compartmentalise a little bit, deal with rugby as a job and step away from it afterwards. That is how I saw dad do it.
"He would be the ultimate professional and then step away from it and be the family man that he is."
Born in Tiberias, Israel, the 28-year-old is right to see this as a crowning glory in a career that has scaled the heights from his 50 caps for Ireland to his central role on the British & Irish Lions tour to South Africa in 2009.
The number eight does not see his role altering one iota until the post-match niceties when he will do his best to honour his mother by withholding any curse words from his speech.
"We have a group of players there who are well able to step up to the plate and lead in any given situation. I will talk like I normally talk even if Brian (O'Driscoll) or Paul (O'Connell) were there," he continued.
"I have been lucky to have some of the best captains around. Brian has been captain for as long as I have been playing for Ireland.
"Paulie was captain of The (British & Irish) Lions. I have Leo (Cullen) week-in, week-out. I have Jono (Gibbes), who was captain of the New Zealand Maoris as my coach as well."
The reward of the captaincy comes at a time when he has been showing a return to form for Leinster, leading his club to three wins this season in the absence of Leo Cullen.
"To be honest, I am quite humbled by it all. The last time I played for Ireland I got to lead them out for my 50th cap. I remember running out on the field thinking it was the best feeling I've ever had in my life.
"To get the captaincy is Roy of the Rovers-type stuff," he said.
All Captain Heaslip has to do now is keep on winning.
IRELAND v SOUTH AFRICA, TOMORROW, 5.30
IRELAND: S Zebo; T Bowe, K Earls, G D'Arcy, A Trimble; J Sexton, C Murray; C Healy, R Strauss, M Ross, D Ryan, M McCarthy, P O'Mahony, C Henry, J Heaslip (capt). Reps: S Cronin, D Kilcoyne, M Bent, D O'Callaghan, I Henderson; E Reddan, R O'Gara, F McFadden.
SOUTH AFRICA: Z Kirchner; JP Pietersen, J Taute, J de Villiers (capt), F Hougaard; P Lambie, R Pienaar; T Mtawarira, A Strauss, J du Plessis, E Etzebeth, J Kruger, F Louw, W Alberts, D Vermeulen.