How close the connection between the two parts of the injunction, "Wait on the Lord," - that has to do with worship and disposition; "and keep His ways," - that deals with walk and work. The outer life must be in harmony with the inner; the inner must be the inspiration and the strength for the outer. It is our God who has made known His ways in His Word for our conduct, and invites our confidence for His grace and help in our heart. If we do not keep His ways, our waiting on Him can bring no blessing. The surrender to full obedience to all His will is the secret of full access to all the blessings of His fellowship. Notice how strongly this comes out in the psalm. It speaks of the evildoer who prospereth in his way, and calls on the believer not to fret himself. When we see men around us prosperous and happy while they forsake God's ways, and ourselves left in difficulty or suffering, we are in danger of first fretting at what appears so strange, and then gradually yielding to seek our prosperity in their path. The psalm says, "Fret not thyself; trust in the Lord, and do good. Rest in the Lord, and wait patiently for Him; cease from anger, and forsake wrath. Depart from evil, and do good; the Lord forsaketh not His saints. The righteous shall inherit the land. The law of his God is in his heart; none of his steps shall slide." "And then follows - the word occurs for the third time in the psalm - "Wait on the Lord, and keep His way." Do what God asks you to do; God will do more than you can ask Him to do.
(Kindle Locations 372-382).