Back, at 36, the oldest player ever selected in an original Lions squad, is just a fortnight away from retirement.
When he returns home on July 10, it will be to take up a coaching role with Leicester, rather than any thought of putting himself through a punishing pre-season training schedule.
Back has achieved every honour in the game, winning a World Cup, a Lions Test series in South Africa, a Six Nations Grand Slam, a European Cup and a handful of Premiership titles.
But ambition and desire burns as brightly as it did when he made his England debut more than 11 years ago.
"To be picked for the Test team is unbelievable, and it is all about taking your opportunities," he said, ahead of Saturday's showdown with the All Blacks at Jade Stadium.
"I've only had one opportunity so far on this tour, and I thought I played pretty well against Wellington. Because of that, I am in the Test side.
"I have achieved a lot with my club and as an international player, and I've won everything you can win, so anything I achieve now is a massive bonus.
"But that doesn't mean I don't want to achieve any more, because to be successful in New Zealand would be fantastic."
Back stepped down from the England scene last year, adding his name to a lengthy list of post-World Cup retirees, yet consistent club form - and an outstanding reputation forged at the forward coalface - meant he was always in Lions chief Sir Clive Woodward's thoughts.
And he has even overcome the setback of a four-week ban, imposed for punching Wasps flanker Joe Worsley during last month's Premiership final, which meant he was unavailable when the Lions took on Bay of Plenty, Taranaki and New Zealand Maori.
"I knew after the final that life would be made more difficult in terms of making the Test team," Back added.
"I always knew that I would have possibly one opportunity, which I knew I had to take.
"My outlook on this tour, once selected, was that I am going to do everything I can to make sure the tour is a success.
"I've played at club first-team level for 17 years, and at international level for over a decade, so the shortage of games is not a problem in my view.
"I've always been able to miss a few games and still be able to get to the right level. I think at this level, when you have the ability to perform and the fitness to back it up, it's all about that mental approach.
"I am still hungry for success. I have enjoyed this tour immensely, and being around the guys on the training paddock just makes you want to achieve more."
Back's battle with revered All Blacks openside Richie McCaw, especially at the critical breakdown area, should go some way towards deciding the contest.
But while Back might concede some six inches in height and almost two stone in weight to an opponent 12 years his junior, he is not remotely fazed.
"In New Zealand, the number seven is a pivotal role and the talisman in most of the teams. It will be competitive and physical at the breakdown, and we've got to win that battle," said Back.
"We are fully aware of the ability of the New Zealanders, from one to 15, at the breakdown area. It is a key area - if you can't keep and retain possession, you are not going to be able to play and score points.
"They won't want this Lions back-line to have quick ball, so I am sure in their dressing room they will be talking about giving us slow ball because they will fear us having quick possession.
"That gain-line battle, that physicality, winning collisions and getting on the front-foot is key to both sides, and on Saturday we go head-to-head and see who wins.
"Without question, Richie McCaw is a world-class player. They are fanatical about rugby in this part of the world, and they've got great players. It is a big challenge.
"I've watched McCaw, and he has been superb, in terms of support play, carrying the ball and in contact areas, but it is not only my challenge, it is the whole of the Lions' challenge."
Some observers feel the Lions huffed and puffed their way past provincial opponents they should have beaten far more convincingly on this tour, suggesting the All Blacks might not be seriously troubled, either on Saturday or in Wellington next week and Auckland seven days after that.
But Back retorted: "Our preparation has been excellent.
"New Zealand, in terms of a game-plan, haven't seen anything, and the 22 guys involved on the weekend have had a full 10 days together preparing for the Test match.
"There has been a step up in every game, without question, and now we feel at a point where we are ready to take off, which we will need to in order to be successful against New Zealand.
"If you play as well as you possibly can, you can beat anyone."