What is the source of the sufferings and problems that afflict humans?

Suffering afflicts man in two ways.

Sometimes God causes problems for a person due to some interests. This type of suffering, which a person has no role in causing, is mainly put on his way to test the character of a person and his growth, and by measuring and empowering a person in the furnace of life, they help him to achieve perfection by adopting the appropriate behavior.

For example, God Almighty says in the Holy Quran:
“And we will reward you with something from fear and hunger and lack of wealth and souls and fruits and patient people.”
And we will certainly test you with something like (like) fear and hunger, and a decrease in property, lives, and crops, and glad tidings of ten patient ones.

But sometimes a person puts himself in suffering with his own hands and gets caught in calamities. It should be noted that wrong thinking and corrupt behavior are the main cause of human being trapped in the circle of corruption and suffering.
A person should search for the root of such problems within himself and solve and cure it by following good thoughts and behavior.