What does Psalm 103:14 mean?

The Lord shows His people compassion partly because He knows we are frail and do not live long. He made man from dust, breathed into his nostrils, and man became a living creature (Genesis 2:7), but man sinned, and he incurred the sentence of death.

Ecclesiastes 12:7 refers to the human destiny as "dust returns to the earth as it was." Between birth and death, human beings bear the physical effects of sin. We experience illness, aches, pain, disease, and weakness. But none of these calamities escape the Lord's attention or His compassion. After all, He formed us in the womb (Psalm 139:13–16). He knows all about us. He even knows when we sit down and get up (Psalm 139:2). Jesus said our heavenly Father knows even the number of hairs on our head (Matthew 10:30) and values us highly. Therefore, we should not fear what someone might do to us.