إِلاَّ الَّذِينَ صَبَرُواْ
Except those who show patience,
meaning, those who show patience during times of hardship and adversity.
In reference to Allah's statement,
وَعَمِلُواْ الصَّالِحَاتِ
and do righteous good deeds,
This means that they perform the good deeds in times of ease and good health.
Concerning the statement,
أُوْلَـيِكَ لَهُم مَّغْفِرَةٌ
those, theirs will be forgiveness,
meaning, that they will be forgiven due to the calamities that afflicted them.
Concerning Allah's statement,
وَأَجْرٌ كَبِيرٌ
and a great reward.
This great reward is due to them because of what they sent forth (of good deeds) in their times of ease.
This is similar to what is mentioned in the Hadith,
وَالَّذِي نَفْسِي بِيَدِهِ لَاا يُصِيبُ الْمُوْمِنَ هَمٌّ وَلَاا غَمٌّ وَلَاا نَصَبٌ وَلَاا وَصَبٌ وَلَاا حَزَنٌ حَتَّى الشَّوْكَةُ يُشَاكُهَا إِلاَّ كَفَّرَ اللهُ عَنْهُ بِهَا مِنْ خَطَايَاه
By He in Whose Hand is my soul! No worry, calamity, distress, illness, or grief strikes a believer, even the prick of a thorn, except that Allah will expiate his sins for him because of it.
In the Sahih it is recorded that the Prophet said,
وَالَّذِي نَفْسِي بِيَدِهِ لَاا يَقْضِي اللهُ لِلْمُوْمِنِ قَضَاءً إِلاَّ كَانَ خَيْرًا لَهُ
إِنْ أَصَابَتْهُ سَرَّاءُ فَشَكَرَ كَانَ خَيْرًا لَهُ
وَإِنْ أَصَابَتْهُ ضَرَّاءُ فَصَبَرَ كَانَ خَيْرًا لَهُ وَلَيْسَ ذَلِكَ لاِإَحَدٍ غَيْرِ الْمُوْمِن
By He in Whose Hand is my soul! Allah does not decree any matter for the believer except that it is good for him.
If any blessing befalls him, he is thankful (to Allah) and that is good for him.
If any harm comes to him, he is patient and that is also good for him. This is (a bounty) exclusively for the believer.
For this reason, Allah, the Exalted, says,
وَالْعَصْرِ
إِنَّ الاِنسَـنَ لَفِى خُسْرٍ
إِلاَّ الَّذِينَ ءَامَنُواْ وَعَمِلُواْ الصَّـلِحَـتِ وَتَوَاصَوْاْ بِالْحَقِّ وَتَوَاصَوْاْ بِالصَّبْرِ
By Al-`Asr (the time). Verily, man is in loss. Except those who believe and do righteous good deeds. And recommend one another to the truth and recommend one another to patience. (103;1-3)
Allah also says,
إِنَّ الاِنسَـنَ خُلِقَ هَلُوعاً
Verily, man was created very impatient. (70;19)