It is important to recognize that human beings are fallible. According to this psalm, When Asaph could not understand God's ways, he became bitter and unhappy. Once he has resolved his unhappiness, he declares that God is the most important aspect of his life. Despite his health failing, Asaph knew God would not fail him in any way. God is regarded as the source of his happiness when he views God as his "portion."
Asaph came to understand that although the wicked seemed to prosper, the godly were unjustly persecuted; by the grace of God, he was on the straight path to eternal joy and bliss, whereas these evil men were on the slippery slope to eternal destruction. It was only a matter of time before these wicked men would be swept forever from the Lord's presence.
Today, it appears as if the wicked prosper abundantly, while the prayers of the godly seem to rise only to steel skies and closed heavens. In spite of this, we have the assurance of our Lord that the sufferings of this life cannot be compared with the glory that is about to be revealed to us because we have a hope that is anchored in Christ and an inheritance that is awaiting us.

Dear Heavenly Father, thank You for showing us in the Psalms that wicked men will suffer the consequences of their wicked ways unless they turn to Christ for salvation. I praise You, Lord, for Your never-ending goodness and grace toward me. It is my prayer that I draw closer to You and proclaim the wonderful works of God in the land of the living, knowing that my days are in Your hands and my future is secured in heaven. 
In Jesus's name I pray. Amen.