Our sufferings (problems) today might not be as great as Paul's. But sometimes they can bring great impact to our lives, they can cause us to be sad, down or stressed out. In other words, we let our circumstances determine our attitude.
We need to learn the secret that enabled Paul to be joyful. We need to know our God in a personal way, focus on His will and have such a faith that God is the sovereign one over all things, He will surely carry us through. Paul did not live for his own interest/ ambition, he lived for God and for the purpose of supplying the word of God to others. The less self-centred we are, the happier we become.
I know what it is to be in need, and I know what it is to have plenty. I have learned the secret of being content in any and every situation, whether well fed or hungry, whether living in plenty or in want.