In light of the challenge and call to be grateful to God, the Psalmist tells us that we should praise Him for the healing He does in our own lives as well as in the lives of people around us. God made and fashioned the human body with an amazing ability to heal and restore itself. He has given mankind knowledge to work on the human body and understand parts of its many complex ways. Through God's guidance and good counseling there is also a spiritual healing that comes over time. The big picture idea is that we should show gratitude to Him because of His intervention in our lives.
 He telleth the number of the stars; he calleth them all by their names.
Scientists estimate there are a total of about 2,500 visible stars on a very clear night (both hemispheres). They also estimate there are 200 to 400 billion stars in our galaxy alone. I also read there are "3 followed by 16 zeroes" stars in the universe. That number is roughly equal to a trillion stars in existence for every person alive today. Now consider all of those stars and look at verse 4, where it says that God calls each of these stars by name. God is marvelously aware of all of the stars as He is the One who created all of them.
Remember this Psalm is about why we praise God. One reason we praise Him is that He cares about our individual lives and at the same time is big enough to create our bodies and universe that is beyond our ability to fathom.