Ireland's impending summer tour is undoubtedly the most arduous of the home nations' end-of-season jaunts, with dates against the all-conquering All Blacks - in Hamilton June 10 and Auckland seven days later - and a one-off Test against the Wallabies in Perth on June 24.
O'Sullivan is well aware that history is against his players prospering Down Under. Ireland have yet to post a win against the All Blacks in 18 meetings - a 10-10 draw at Lansdowne Road in 1973 was the closest they have come to a prized victory.
Their record against Australia offers more encouragement, with seven wins in 24 clashes - three of those were on Australian soil with the most recent success back in 2002 at Lansdowne Road.
But Irish rugby's best season since the dawning of the professional era - with the Triple Crown, European Cup and Celtic League trophies all safely in the vault - has O'Sullivan and his players brimming with optimism.
The British & Irish Lions coach said: "This tour is coming off the back of a long season - what was for most players a very successful one - but everyone is very much switched on to the task at hand.
"Playing New Zealand and Australia in their own backyards certainly sharpens the mind. The guys from Munster and Ulster (after their efforts in the European Cup and Celtic League) have come into camp very much on a high and it's a great boost for everyone involved.
"In turn, we had a very good Six Nations campaign and we've sort of helped each other on the way - the provinces feeding the national side and vice versa.
"We've a tough few weeks ahead of us - taking on New Zealand twice and then Australia on three consecutive Saturdays - but we wouldn't have it any other way."
O'Sullivan's charges began the international season back in November with a 45-7 defeat at the hands of New Zealand, shipping five tries. A week later, the Aussies took a 30-14 victory away from Lansdowne Road.
Having overseen five wins in six outings since that loss to the Wallabies, O'Sullivan admitted: "I know we have the ability to turn those results around - it was early in the season for us and we were missing key players. We've a much better balance going into these games.
"Four years ago, we ran the All Blacks very close (15-6) in the first Test in Dunedin and there is a good deal more experience in our side now. We've got Brian O'Driscoll and Paul O'Connell back now - they were both missed in November.
"We were very happy with the Six Nations. Yet we're aware that we haven't won big matches on tour for some time so we'll be giving it all we've got."