The psalmist cites his purpose of writing in verse 18 as it states that this Psalm was written so that a future generation may learn to praise God. The idea of this Psalm is not about remembering the author who lived roughly 3,000 years ago and how much he suffered while writing this Psalm. Rather, the idea being expressed here is for all of us to understand that God rules over our lives and we can trust Him to not only guide our lives, but He promises us great things just for believing that He exists. After all, we can be eternally forgiven of our sins just by trusting in God’s perfect payment for our sins.
The essential idea of these verses is to always remember that God is well aware of what we personally go through in our lives. He knows the pain we are feeling at any moment. We would do well to remind ourselves that if God is big enough to make this world in the first place, then He is also big enough to understand all of our individual problems and issues in our lives.
The next great reminder of these verses is simply to remember that none of us will live forever as we currently understand life to exist. It is only by trusting in the God who created everything that we actually can and will live forever.
As the writer was earlier remembering his pain, he also remembers and trusts in a God who is in charge. This God will one day rescue him in this life or in the life to come He will literally rule over this world. Although God may or may not rescue us out of our current predicament, that does not negate the idea that He does rule. God is in charge and He will guide us to eternal life just because of our trust in what He has done, is doing and will do in our lives.