A complete answer to your question would be very long. Here are a few thoughts.
James says the thing we do not want to hear:
2 Consider it pure joy, my brothers and sisters, whenever you face
trials of many kinds, 3 because you know that the testing of your
faith produces perseverance. 4 Let perseverance finish its work so
that you may be mature and complete, not lacking anything. 5 If any of
you lacks wisdom, you should ask God, who gives generously to all
without finding fault, and it will be given to you. 6 But when you
ask, you must believe and not doubt, because the one who doubts is
like a wave of the sea, blown and tossed by the wind. 7 That person
should not expect to receive anything from the Lord. 8 Such a person
is double-minded and unstable in all they do. (James 1:2-8)
To reap benefits from suffering requires time and faith. The faith comes in because the amount of time is seldom told to us. Overcoming my fear of death took a few months following my becoming a Christian. Pulling out of depression took about three years (on top of the years of depression that preceded my coming to faith). Overcoming severe anxiety accompanied by many physical manifestations took decades. Learning to trust God with my finances took fifteen years, during which I twice was brought to the edge of bankruptcy. Each set of trials lasted a different length of time. Some character flaws of mine have yet to be resolved, despite over thirty years of prayer and patience.
There is another dimension to suffering that must be spoken. The benefits of some of our sufferings do not accrue to us but to others, like our children, friends or even strangers. Years ago I three times visited a woman dying of rheumatoid arthritis. I prayed for her, read the Bible to her, and gave her a cassette of Christian music. Despite her severe pain, she maintained her faith in God. Six months after I met her, she died. Her suffering may seem to have reaped no benefit for her, but listen to what a friend said at Janet's funeral. "When you were with Janet, it was like the Holy Spirit was pouring out of her." The combination of her suffering and her faith made her a suitable vessel for the Holy Spirit to work miracles. When I left Janet's side after our first meeting, I wept bitterly. However, within the hour, my tears stopped, peace filled my heart, and then joy. I have not experienced that magnitude of joy in my life before or since. It lasted for a week. From that day forward I was delivered from depression.
The Book of Job illustrates the power of suffering well. Job's suffering was great and it sharpened his mind. He listed all the problems that he needed a savior to fix: his physical and mental health, relationships, finances, forgiveness for sin, resurrection from death, ransom payment, and more. He also needed that savior to not terrify him the way God did. He wanted a fellow man, a good friend, full of compassion and meekness who was approachable to intercede with God on his behalf. Job basically wanted a man with the power and influence of God. Without knowing his name, he knew he needed Jesus. Then when his friends laughed at the idea that a "son of man" could be of any use, God rebuked them and said that Job had spoken correctly. Job's sufferings and insight and God's response defined what a savior had to be and to do. Job's story then became the first of the Bible to be written, answering Job's prayer that his experiences be written down and preserved forever. That is what Job's suffering did for the world. We can pray for relief, but we should also pray that we can be an example of faith in the midst of suffering so that others may find hope. The steadfast hope of people who have no rational reason to have such hope is a miracle that can change the world.
A few other ideas:
- suffering teaches us to pray often and with fervor
- our suffering inspires other people who have the love of God in them to help, encouraging community and fellowship and gratitude
- Ecclesiastes 7:4 says, "The heart of the wise is in the house of mourning, but the heart of fools is in the house of pleasure." Thus suffering leads to wisdom.