Seek the LORD, and His strength: seek His face evermore.
In these three verses, the focus is on what every believer should strive to do with his life. First we should "Glory (trust) in His name". The idea is that if we can take the time to appreciate all He has done for us, it should cause us to appreciate Him all the more.
The last part of verse 3 as well as verse 4 speaks of seeking Him. We should seek Him as this is an act of worship that gives us the strength and ability to make a difference for Him with our lives.
 Remember His marvellous works that He hath done; His wonders, and the judgments of His mouth;
As long as Israel remembered God’s miraculous works, the Lord remembered His covenant promises (see verse 8).
 O ye seed of Abraham his servant, ye children of Jacob his chosen.
Verses 3-5 focused on whom it is we are to worship, that is, God. Verse 6 focuses on who does the worshiping, which are all the Israelites. Remember that this Psalm focuses on specific aspects of the history of Israel and it is in effect written to Israelites.
As Christians today, we can enjoy the same privilege of trusting in God for our salvation than those of a literal Jewish heritage.
The descendants of Abraham and Isaac were God’s “elect” people, who enjoyed the prosperity in the land designated by the Lord.