"GOOD & BAD days are given to people by turns to TEST them"

إِن يَمۡسَسۡكُمۡ قَرۡحٌ۬ فَقَدۡ مَسَّ ٱلۡقَوۡمَ قَرۡحٌ۬ مِّثۡلُهُ ۥ‌ۚ وَتِلۡكَ ٱلۡأَيَّامُ نُدَاوِلُهَا بَيۡنَ ٱلنَّاسِ وَلِيَعۡلَمَ ٱللَّهُ ٱلَّذِينَ ءَامَنُواْ

"If a wound has touched you, be sure a similar wound has touched the others. And so are the days (good and not so good), We give to men by turns, that Allah may test those who believe"

(Qur'an 3:140)

Commentary: Allah S.W.T says in the Holy Qur'an "Do you think that you will enter Paradise before Allah tests those of you who struggle (in His Cause) and (also) tests those who are patient?" (3:142) Also, He S.W.T says "We shall test you with evil and with good" (21:1). Good and bad days are a test from Allah to examine which of His slaves are thankful and humble during the good times. And, patient and content with the decree of their Lord during the bad times.