I always (arrogantly) disregarded this advice as a young'n because I felt fine at the time. Twenty years later I now have a seriously arthritic neck / back. Very painful everyday.
Caveat emptor.
Pomodoro technique helped for a while, until it was interrupting actual work. Now I take breaks when I remember I need a break.
But sometimes it's inevitable and I can't get into the zone.
I then take Ritalin.