Some of the world's suffering is the Devil's doing.
Job 1:12-19; 2:6-7
Acts 10:38
2 Timothy 2:26

Some of the world's suffering is self-inflicted, often due to greed.
Proverbs 15:27
1 Timothy 6:9-10
James 4:1-2
James 5:1-3

We often bring on suffering by sin and disobedience.
Genesis 42:21
Job 4:8 reap the same
Psalm 107:17
Jeremiah 30:15

Suffering is sometimes God's loving chastisement.
Proverbs 3:11-12
Hebrews 12:5-12
1 Corinthians 11:32
Revelation 3:19

God has a good and loving reason when He allows suffering.
Genesis 45:4-8; 50:20
Psalm 119:71
Romans 8:28

God comforts and strengthens us when we suffer.
Matthew 5:4
John 14:18
1 Peter 5:10

Suffering can draw us closer to the Lord and teaches us His ways.
Job 23:10
Psalm 94:12
Psalm 119:71
Isaiah 48:10
John 15:2
Hebrews 12:9-11

Other good fruits of suffering:
Deuteronomy 8:2,16 (humility)
Romans 5:3b (patience)
Ecclesiastes 7:2-3 (wisdom)
2 Corinthians 1:4 (compassion)

Keep the faith.
Job 13:15a
Acts 20:23-24
Romans 12:12a
2 Corinthians 7:4b
Philippians 3:8
Hebrews 11:25-27
James 5:10-11
1Peter 4:13,16

Rewards in Heaven for earthly suffering
Romans 8:18
2 Corinthians 1:7
2 Corinthians 4:17
2 Timothy 2:12a
Revelation 21:4