A question that, for many, is imponderable, but it is something that has certainly been on the minds of football's GOATs
When a footballer crosses the threshold of 30, it is usually not long before their playing days begin to wind down, such is the physical and mental demand of playing the game.
Cristiano Ronaldo crossed into his thirties in 2015 and Lionel Messi followed him into that twilight zone two years later in 2017.
Yet, despite time's unrelenting procession and the natural effects of aging which spare no one, the pair continue to bedazzle at the highest level for club and country.
There has been little sign of either player slowing down dramatically but, given their age profile, the question for many remains: how much longer can they play for?
How much longer can Lionel Messi & Cristiano Ronaldo play for?
We cannot be entirely certain just how much longer Messi and Ronaldo will be able to play for, because there are so many considerations to take into account.
However, with ideal conditions, it is not inconceivable that the two could play at the highest level until they are 40.
The average age for a footballer to retire, according to the PFA, is 35. Ronaldo has already passed that point, while Lionel Messi will do so in 2023.
A cynic might argue that they are in bonus territory now, but Ronaldo and Messi can take heart from the fact that there have been a number of high profile examples of individuals playing into their late thirties and even past 40.
Goalkeepers are more likely to play well into their thirties, which is not surprising when one considers the relative lack of punishment a goalkeeper's body takes during the course of a career, but there are plenty of outfielders who have defiantly ploughed through too.
AC Milan icon Paolo Maldini hung up his boots in the summer of 2009 just before his 41st birthday, Ryan Giggs played for Manchester United at the age of 40 and Javier Zanetti remained a key influence at Inter up until 40 as well. Italy and Roma legend Francesco Totti retired in 2017 at the age of 40, while Sir Stanley Matthews even played until he was 50.
The only player remotely close to Ronaldo and Messi in terms of scoring goals who is still playing is Zlatan Ibrahimovic, and the Swede, who signalled his intention to keep playing as long as he is healthy enough to do so, has been tipped to continue starring for Milan past his 40th birthday.
Ronaldo and Messi are both fully aware that time is running out, but it remains unclear when their respective adventures will come to an end. Perhaps understandably, they both seem reluctant to set a date.
In 2019, as he collected his record sixth Ballon d'Or, Messi conceded that "retirement is approaching", but added: "I hope, God willing, that I keep playing for many more years."
Ronaldo, meanwhile, admitted that he could not promise "20 more years", but stressed that he would give his best for as long as he could.
“As I celebrate my 36th birthday and my 20th year as a professional footballer, I’m sorry that I can’t promise you 20 more years of this," the Portuguese wrote on Instagram in 2021. "But what I can promise you, is that as long as I keep going, you’ll never receive less than 100% from me!"
How can Cristiano Ronaldo & Lionel Messi prolong their careers?
Given that Ronaldo and Messi are already excelling well into their thirties, the easy answer when it comes to the question of how to prolong their careers, is to keep doing what they are doing.
However, it is true that their bodies will naturally change as they get older, so they will have to be conscious of the need to make any adjustments to their current practice.
Healthy diet & efficient training
Both players follow personalised training regimes and specific, healthy diets, which have no doubt contributed to their success over the years.
Ronaldo consumes a high protein diet, with fish featuring prominently, complemented by whole grains and fresh vegetables, avoiding vices such as sugary foods. Messi also adheres to a strict menu, including chicken, nuts, whole grains and fresh fruit among other things.
Adapt to different roles
If the iconic duo hope to prolong their respective careers, they will have to be open to the possibility of changing their roles within their teams, and this is already happening, with both of them dropping deeper in an effort to dictate play at their pace.
The sort of lung-busting runs that characterised Ronaldo's early career are being phased out - though he is still capable of pulling them off - while Messi's penchant for dribbling has been curbed somewhat in order to minimise the risk of succumbing to heavy tackles.
Play less
It is no secret that playing a lot of games increases the risk of injury, not only from a physiological perspective, but also from a plain probability standpoint. While players like Ronaldo and Messi are used to playing every minute of every game, they will have to get used to sitting certain games out or having their time on the pitch curtailed so that their health can be protected.
Retire from international football
Tied in with previous points, Messi and Ronaldo's playing career could arguably be lengthened if they retired from international football. By its very nature, international football requires a lot of travel - particularly for Messi, who has had to take a lot of trans-Atlantic flights to play for Argentina - and that in itself can take its toll on an individual.
Of course, international commitments also mean more games and minutes on the field, which, as mentioned, can contribute to a heightened risk of injury.
Be prepared to play at a lower level
It may seem unthinkable for the likes of Ronaldo and Messi to drop below the absolute elite level and it is entirely possible that they would prefer to bring the curtains down on their careers at the top, but they could probably play as long as they felt healthy if they were willing to drop down leagues.
Performing in the Champions League or any one of Europe's top five leagues demands an intensity that simply cannot be sustained forever and they may be able to get away with playing longer if the environment they are in is less taxing.
What will Cristiano Ronaldo & Lionel Messi do when they retire?
It's not clear what Ronaldo will do when he retires from playing, but he will have no shortage of things to keep him occupied, not least his various business interests.
In 2019, he revealed that he was not so interested in coaching, meaning he's unlikely to follow in the footsteps of ex-players such as Zinedine Zidane or Pep Guardiola in becoming a manager.
He has joked that he would like to do some acting, while a more serious consideration is his desire to complete studies, potentially at university, in order to deepen his business nous.
Coaching is always an option to ex-players, while punditry and ambassadorial roles are other avenues that many high profile stars have taken.
Until that time comes, however, we may just enjoy their talents as much as we can!