This verse concludes with David's admonition to wait on the Lord. It is imperative that all who wish to serve the Lord heed this admonition. Our timetable may differ from God's. It is human nature to wish for an immediate answer to our prayers, but the Lord is never in a hurry. We may not receive an immediate response from Him, but He has promised to respond when help is needed. 
Faith is strengthened as we wait for the Lord to work in the difficult circumstances of life through patient endurance. Similarly, faith is sometimes challenged during those long and painful periods of life. This is when patience is needed as we depend on the Lord to act in prayer, praise, and thanksgiving while waiting for his promises to be fulfilled.
It is essential that we wait confidently for the Lord to act on our behalf. We will be enabled to be of sound courage and to rely on the Lord when we accept God in His Word and trust Him unquestioningly. Even though our inner fleshly nature and outer distressing circumstances scream at us, it has been promised to us that we will have strong hearts.

Dear Heavenly Father, I am too often tempted by my old sin nature to take control of my life instead of abiding in Your promises. I pray that You will teach me patience and courage so that You will always be in control of my life. All I need to do is wait quietly for You to act on my behalf. I am also called upon to confidently wait for You with prayer and worship and a heart of thanksgiving and praise. 
In Jesus's name I pray. Amen.