(Try reading these verses in a different translation each day.)
Who is the Shepherd?
How does this answer comfort you? Bolster you?
Because the Lord is your shepherd, you shall not want. How do you define want? Ask God to show you his definition.
Notice the verbs: makes and leads. What does He make us do? Where does he lead us?
Green pastures and still waters both carry the idea of rest. How and why can we rest in these two places?