I'm reading Henri Joly's "The Psychology of Saints", written a century ago and currently published by RC press and there's a crux of a line near the end:
A superficial psychology, or one which deals only with persons very far removed in character from the saints, would have us believe that pleasure stimulates action and that pain dulls it. Pain dulls action when it saps the strength, when it is dreaded and the person either cannot or will not turn it to good account, or when effort would only end in creating irreparable evil. But this is never the case with the saints. With them sufferings ...do not weaken the soul, for they are the fruit of the vigor of a soul which loves and is desirous of self-sacrifice. (emphasis mine)The "cannot or will not" is a key difference it seems. How does one know whether one is dealing with cannot or will not, seeing how the latter is culpable and the former not? We know now that pain in the psychic sense that dulls action can be of at least two types: one, simply a chemical deficiency, a deficiency of the level of the neurotransmitter serotonin in the brain. It could also be, as Joly mentions, related to sensuality which "destroys constancy and renders the heart narrow" or "is brought on by Satan, who, endeavors to excite 'trouble, disgust, sadness and scruples of conscience.'"
Joly mentions elsewhere that the saints were not indifferent to innocent pleasures, "which, according to Alfred de Musset, help us to enjoy life, or at any rate, make the burden of it easier to bear. They do not seek them for themselves, but they endeavor to procure them for others, especially for the young, or the sick and afflicted."
A crucial point Joly mentions is that the motive for all action must come out of a love for God, rather then self, which means that "those who have charge of a soul [must] have seen what the object of its love is to be...for we must not forget that 'it is the property of love to change the soul into the thing which it loves'". But is the object of our love so unvarying as this line suggests, as if we love only self at all times, or only God at all times when in practice it seems more irregular? (Or does the irregularity suggest, by definition, the object is self?)
(Feel free to email me your response to the question. A free Guinness to the first person with the correct answer. *grin*)
I guess such complexities highlight the wisdom of St. Pio's line: "Pray, hope, and don't worry."