Spiritual struggles and labors generate gladness in the soul, so long, that is, as the passions have been stilled; for what is difficult for those who are still dominated by the senses, is easy and even delightful for an aspiring soul that through its holy exertions has acquired a longing for God and is smitten with desire for divine knowledge.
For the sense-dominated, the labors and struggles for virtue, opposed as they are to bodily ease and indulgence in sensual pleasure, are difficult and seem very harsh, for in such people the brackish taste of pleasure has not yet been washed away by the flow of tears. But the soul that abominates pain-inducing pleasure, and has rejected comfort along with the self-love of the body, feels the need for and embraces such labor and struggles. One thing alone distresses it: slackness in its labors and indolence in its struggles.
Thus what for those still dominated by the senses is the source of bodily content, is for the soul that aspires to what is divine a cause of distress. And what for the aspiring soul is a cause of spiritual gladness, is for the sense-dominated the cause of pain and anguish.
~Nikitas Stithatos
Prayerful Life 