Time waits for no-one.
In an industry as relentless and brutally competitive as professional football, reaching the top level is hard enough, let alone staying there for 20 years.
More than just talent, it takes a special mindset - a remarkable amount of focus, dedication and drive, especially with the increased demands of the modern era. Few are up to the challenge.
When James Milner came on for Liverpool against Southampton at Anfield on Saturday, it brought up his 600th Premier League appearance.
"It's a big number isn't it?" Milner told BBC Sport afterwards.