To run a sub-3, you have to run 42km at a 4:15 pace...

I guess you have to be comfortable running at a 4:30 pace even on normal days
That's insane...
For me, running at a 4:15 pace is almost near my maximum effort, and I feel my legs getting incredibly heavy after just 2km
For an average runner like me, that's a record I'll never be able to achieve in this lifetime