The focus of Psalms Book IV and the Summary Psalm 149 is on the work of the glorified saints in serving as mediating priests under Christ.
Psalms 90-100 are prophetic, having a definite time progression, especially referencing the time frame between the Feast of Trumpets to the Last Great Day.
The Millennium or God's rest will be an exceedingly busy time, a time when all of humanity will be converted, a time everybody will be on the same trek.
The Sabbath is an antidote to the weariness we experience. It recalls God's pausing after completing His physical creation, focusing on the spiritual creation.
Focusing on material and temporal things undermines faith. The Sabbath is holy time, created for building faith, energizing our minds for fellowship with God.
If we patiently endure, trusting in God's faithfulness to bring us to completion, there will be a time when we will attain the rest we desperately yearn for.
The ancient Israelites resisted the gospel, refusing to mix it with actual obedience. What they heard never became a part of their lives; Egypt never left them.
In our hectic culture, we commit far too little time to God, depriving ourselves of the Holy Spirit and attenuating the faith required to draw close to God.
We must emulate Christ, who learned through suffering, preparing Himself for His role as High Priest. Giving in alienates us from the fellowship with God.