Depression

Eschew anxiety (al-hamma) and depression (al-ghamm) for through these twain will transpire a darksome affliction

Bahá’u’lláh, Tablet of Medicine

To engage in some profession is highly commendable, for when occupied with work one is less likely to dwell on the unpleasant aspects of life.

Bahá’u’lláh, Tablets of Bahá’u’lláh, p. 175

According to what I have heard, thou hast experienced a great financial loss. Do not feel sorry, for thou wilt be compensated. I hope that whatever thou hast lost will come back to thee. But this material loss is not a very grave one; it is for a time and shall pass away. Alhamdallah! [Praise be to God!] -- that thou hast a share in the Kingdom of God and art receiving gifts from the treasury of the Holy Spirit. Do not feel sorry; do not brood over the loss; do not sit down depressed; do not be silent; but, on the contrary, day and night be engaged in the commemoration of thy Lord in the greatest joy and gladness.

‘Abdu’l-Bahá, Tablets of ‘Abdu’l-Bahá v1, p. 132

Be not the slave of your moods, but their master. But if you are so angry, so depressed and so sore that your spirit cannot find deliverance and peace even in prayer, then quickly go and give some pleasure to someone lowly or sorrowful, or to a guilty or innocent sufferer! Sacrifice yourself, your talent, your time, your rest to another, to one who has to bear a heavier load than you.

‘Abdu’l-Bahá, source unknown

Be thou not unhappy; the tempest of sorrow shall pass; regret will not last; disappointment will vanish; the fire of the love of God will become enkindled, and the thorns and briars of sadness and despondency will be consumed! Be thou happy; rest thou assured upon the favors of Bahá', so that uncertainty and hesitation may become non-existent and the invisible outpourings descend upon the arena of being!

‘Abdu’l-Bahá, Tablets of ‘Abdu’l-Bahá v3, p. 557

But these episodes shall pass away, while that abiding glory and eternal life shall remain unchanged forever. Moreover, these afflictions shall be the cause of great advancement.

‘Abdu’l-Bahá, Selections from the Writings of ‘Abdu’l-Bahá, p. 238-239