It can be as easy as a torn ACL, bad concussion or a dislocated shoulder.
An injury, unlucky season or team picking that doesn't go as planned can pave the way to an early retirement in a professional sports player's career - and bring with it an uncertainty of what's next.
The Building and Construction Industry Training Organisation has expanded the support they have to sports players, to help future proof their careers and balance the rugby boots and work boots.
It introduced the Enterprise Package this year, which offers rugby and league players at a national level a taste of building before they finish playing sports.
BCITO chief executive Warwick Quinn said their past packages for sports players could only be completed in a certain amount of time, but this one could be done over a longer period.
"They can pick up skills while they're still playing their sport and they can hit the ground running when they retire."
Quinn said the Enterprise Package was more flexible, allowing players to learn building theory and do practical components when they could.
"They can play sport in the season and do their apprenticeship in other months."
Training advisers also checked in with apprentices to make sure they were on track and managing to balance their sporting commitment and training.
Quinn said it helped players to know they had something to fall back on.
"We recognise as a professional sports player you are unlikely to play for your entire life ... you need to able to transition into a role without having to start from scratch again."
The industry also needs thousands more apprentices coming through the pipeline to meet demand, he said.
"We've got a bottomless pit to fill over the next five years ... anything we can do to add to the supply shortage we are willing to investigate."
There were currently three New Zealand All Black Sevens players, nine Warriors and 13 Super Rugby players on the package's roll.
Twenty nine per cent of retired rugby players also have a trade qualification.
One of them is former All Black Chris Jack, who was 34 when he started a career in the industry.
After a stint playing professionally in Japan during 2012, Jack was forced to re-evaluate his options after injuries and diminishing form got the better of him.
Jack said it was like "leaving school again".
"I had a whole lot of skills that I'd learned in rugby that I didn't quite know how to put across to the real world,
"Going into the construction industry, I had no experience and it was like starting again all over for me ... it was a bit scary at the start."
Jack said being able to do his apprenticeship while playing rugby would've been great.
"When I started my career, I had no skills or no knowledge of the industry as such and if I had that, or had done my apprenticeship or some of my work beforehand, then it would've saved me that four years."
Jack said he soon found the industry was the place for him.
"Being a rugby player, you're doing a team sport and you rely on other people and when you get into the construction industry, it's a similar sort of feeling."
Quinn said the latest initiative had been positive among potential apprentices, and their supporting associations.
"We are getting feedback from coaches that players in an apprenticeship programme are performing better on the field – more rounded, more grounded."
Wellington-based Sam Smith is doing a building apprenticeship with BCITO, playing representative rugby for Wellington and trialling for the U20 All Black's team.
He said his boss was flexible and let him have time off work for his camps and that learning a trade made him feel more grounded for the future.
"It's a good opportunity to learn something else and you always have something to fall back on. You can't really rely on rugby because not everyone's going to make it."
Quinn said BCITO now had a project team dedicated to sports liaison to grow the initiative across the country and with overseas players.
"Although rugby has been our focus this year, we are working with more sports organisations to make the Enterprise Package available to a whole raft of sports."