Yes, his N=1 seems atypical,

He said he exercised for a year, so I don't think not-exercising-enough was the reason he (thinks he) didn't gain muscle.

it's true that those who don't enjoy physical activity, don't sustain it (usually the virtuous, or obsessive, cycle closes only after making enough progress and/or caring desperately about appearance to overcome the initial resistance)

Precommitment devices FTW!