Comment by Fricken

A person who gets their doctor recommended 150 minutes of moderate aerobic activity each week shouldn't have much difficulty adapting their bodies to distance cycling well enough to hit comparable numbers after a handful of training rides. Elites can hold pace for those distances at 50 km/hr, which is faster than me doing an all-out sprint.

And one doesn't have to do 100km all at once. A 10km commute each way over a 5 day workweek is a much less intimidating prospect.