A story is told about a man often walked through a cemetery on his way home. One night, though, unaware that a new grave had been dug in his path, he tumbled in. For some time he struggled to get out of the 7 foot deep grave, but finally gave up and settled down for the night.
An hour later, a farmer out hunting came walking through the cemetery and he too fell into the grave. He began a desperate attempt to get out, unaware that there was anyone else in the grave.
The first man listened to him for a while, while he was struggling to get out. Then he tapped the farmer on his shoulder and said, “I’ve been here all night. But I couldn’t get out.”
The farmer got out of there in no time!
How many times have we thought that we can get out of any problem on our own strength? Asaph knew the limitations of life. He said my flesh and my heart will fail. “My flesh and my heart” here means “my whole being.” (See Ps. 84:2). “Fail,” from kalah, means, “to be completed, finished, accomplished, ready; to be at an end.” Yet in this context, it may carry “the idea of exhaustion, being entirely consumed.” (TWOT/OTWS). It does not mean physical death here, but physical exhaustion, a physical failing. It refers to “the physical weakness that sometimes precedes death (see Job 33:21; Pss 71:9; 143:7; Prov 5:11).” The idea here is that our bodies fail. Our physical bodies get exhausted, with many trials and troubles. Life is limited.
But “God is the strength of my heart,” Asaph said, “and my portion forever.” “Strength” is from the Heb. tsuwr, “a cliff; a rock or boulder; fig. a refuge” (Strong) In the Near East, a rocky cliff or rocky summit is a place of protection from the sun and the rains. It can also be a place of advantage during warfare. If you are above ground, on a rocky height, that is an advantage over your enemies below.
Asaph is saying that God is my strength, my stability, my refuge, my protection, and my advantage. He recognized the limitations of life. But he also realized that God is the true source of strength in his limited life.
We don’t have stability in life. But you can say with Asaph, God is my stability. We don’t know how to protect ourselves. But you can say today, God is my protection.
“Portion” is from cheleq, “an allotment, inheritance, part” (Strong). What does “portion” mean here? Remember that Asaph was a Levite. Levites served as assistants to the Aaronic priests. They were the maintenance men of the Temple. As a Levite, Asaph lived by the tithes of other people in Israel (Num. 18:21-24; Deut. 10:9; 18:1-2). The tithes are his portion, his allotment, in order to live. Asaph said that “God is my portion forever.” He is saying that God is my source of life, my sustainer, my preserver, my provider. Say with Asaph today, God is my sustainer, my preserver, and my provider. God is my portion forever.
Note the word, “forever.” Asaph will lose everything on this earth, but God is his inheritance forever. This is the same thing with you and me. We go into this world with nothing. We will come out with nothing. The things you hold dear today will just fade away someday soon. But if you have Christ, you have everything! If you have Christ, you have everything that lasts, for eternity! God is our portion, not just for today, but forever!
 John H. Stek, “Psalms,” inThe NIV Study Bible (Grand Rapids, MI: Zondervan, 1985), 861.
 Robert B. Chisolm et. al, in The NET Bible (n. p.: Biblical Studies Press, L.L.C., 1996-2007), 999.
 Stek, “Psalms,” in NIV Study Bible, 861.