Two runners build a fire.
Runner One empties half a bottle of lighter fluid into the pit and throws in a match.
WHOOOOMP.
Huge flame. Everybody looks. Garmin probably awards a badge.
Three minutes later: cold dirt.
Runner Two stacks kindling, then small wood, then larger logs. Nothing spectacular happens for a while. Nobody uploads it to Strava. Twenty minutes later, the fire is ripping — and it stays hot all night.
You know where this is going.
Logs = easy running, aerobic volume, long runs, boring consistency. They catch slowly. Burn quietly. Last. That's your aerobic base.
Lighter fluid = intervals, VO₂max work, aggressive race-pace sessions and other expensive forms of suffering. Useful? Absolutely. Foundation? Negative.
The problem is psychological. Intensity feels like progress. Heavy breathing. Fast splits. Wobbly legs. Watch makes exciting noises. Easy running gives you almost none of that dopamine theater.
So runners get impatient and start spraying lighter fluid on an unfinished pile.
Hot flash. Cold ash.
Repeat until injured, exhausted, plateaued, or posting online about how Zone 2 "doesn't work."
Beautiful number. Terrible outcome. The training load was enormous. The intended training purpose was not accomplished.