Chapter 18: The order for reciting the psalms (paragraphs 5-6)

After all, we read that our holy Fathers had the energy to fulfil in one single day what we in our lukewarm devotion only aspire to complete in a whole week.

(From para. 6 of Ch. 18 of Saint Benedict's Rule, trans. by Patrick Barry OSB, 1997.)

I don't think that devotion, as St. Benedict speaks of it, is about spiritual athleticism. Rather, I think it's about an expanding experience of divine energy, and its ability to set our lives aflame.