Everyone, no matter how far along in spiritual development, is likely at times to experience weariness, an "inability to carry on," and meaninglessness.
Even one who has followed the path of Torah and mitzvot wholeheartedly all his life can be overtaken by such fatigue and indifference.
The root of the problem probably lies in a prior experience, somewhere along the way, of backsliding and "falling."
Even the most pious and scholarly are not immune.
The only cure for fatigue of this kind is spiritual renewal, and this, in turn, must come from outside. "A prisoner cannot effect his own release."
Herein lies the importance of comrades and close friends, with whom one can share one's concerns and from whom one can gain encouragement in times of crisis.
Dark feelings often result from a sense that one has exhausted his own inner resources and cannot break out of the closed circle of his life.
Talking the matter out, even indirectly, and examining it in the broader perspective of the fundamental sources of illumination can restore the soul to life.
Even one not so afflicted is well advised to seek out renewal in contact with others, whenever the opportunity presents itself.
To be sure, there is a danger of overdoing social contact, and rousing discussions do not always yield results.
But it is important to make the effort and look for such reinforcement.
If one has a rabbi or teacher who can serve one as a source of enlightenment, one should meet with him regularly.
Lacking such a mentor, one should turn to friends, or even strangers, to help him sustain his inner life.
In the final analysis, the secret of fellowship is to be found in this verse: "For should they fall, one can raise the other; but woe betide him who is alone and falls with no companion to raise him!" (Ecclesiastes 4:10).
Just as ups and downs are a part of life in general, so crises and misgivings are part of the life of faith.
Weakness does not afflict everyone at the same time, so that when one is afflicted there are others around to help him up.
–Rabbi Adin Steinsaltz
From Teshuvah, by Rabbi Adin Steinsaltz