Always turning to Allah, placing one's trust in Him, and being satisfied with His care and protection --- these are among the most important of factors that bring happiness to the believer.
(Do you know of any who is similar to Him? [Of course none is similar or co-equal or comparable to Him, and He has none as partner with Him].[There is nothing like Him and He is the All- Hearer; the All-Seer].) (Qur'an 19: 65)
('Verily my Wali [Protector Supporter; and Helper etc.] is Allah who has revealed the Book [the Qur'an], and He protects [supports and helps] the righteous.) (Qur'an 7: 196)
No doubt! Verily the Auliya of Allah [i.e. those who believe in the Oneness of Allah and fear Allah much (abstain from all kinds of sins and evil deeds which He has forbidden), and love Allah much perform all kinds of good deeds which He has ordained)], no fear shall come upon them nor shall they grieve.)
(Quran 10: 62)