Ibn Qayyim al-Jawziyyah said:
"The destruction of the heart occurs by security [in this Dunya] and negligence; its fortification occurs by fear and remembrance. If the heart renounces the pleasures of the Dunya, it settles upon the [pursuance of] pleasures of the Hereafter, and amongst those who call towards it. Should the heart become content with the pleasures of the Dunya, those pleasures [of the hereafter] cease [to continue].
Yearning for Allah and his meeting is like the... gentle breeze blowing upon the heart, extinguishing the blaze of the Dunya. Whosoever caused his heart to settle with his Lord shall be in a state, calm and tranquil, and whosoever sent it amongst the people shall be disturbed and excessively perturbed. For the love of Allah shall not enter a heart, which contains the love of this world, except as a camel, which passes through the eye of a needle.
Hence, the most beloved servant before Allah is the one whom He places in His servitude, whom He selects for
His love, whom He causes to purify his worship for Him, dedicates his objectives for Him, his tongue for His remembrance, and his limbs for His service.
The heart becomes sick, as the body becomes sick, and its remedy is al-Tawbah and protection [from transgression]. It becomes rusty as a mirror becomes rusty, and its clarity is obtained by remembrance. It becomes naked as the body becomes naked, and its beautification is at-Taqwa. It becomes hungry and thirsty as the body becomes hungry and thirst, and its food and drink are knowledge, love, dependence, repentance and servitude." From: Al-Fawaa’id [pg. 111-112]