Asaph says in Psalm 73,
My heart and my flesh may fail
Even after proclaiming that God is better than anything in heaven and earth, Asaph still knows his heart will be fickle and, left alone, will want false things again.
Thankfully, For the follower of Jesus, our hope is not our flesh and our heart. Asaph continues,
But God is the Strength of my heart
In his book Faith on Trial, Martin Lloyd Jones writes,
I know that I can say that, even though a day may come when I shall feel the foundations of life shaking beneath me, God will be a rock that will hold me. He cannot be moved; He cannot be shaken. He is the Rock of Ages, and wherever I am, and whatever may be happening, however my physical frame is behaving and even when the things of earth are passing away, God the Rock will sustain me and I shall never be moved, “God is the Rock, the strength, of my heart, and my portion forever.
What a glorious promise! God is our Rock, our Strength. We are not. May we trust in this great and glorious God who is our Strength today.