The writer of the Letter to the Hebrews mentions that there is a rest that God has prepared for His people which some have not entered at all (He.4:1). Is it possible that any of us has failed to enter into that rest till now? To know that, we must understand what this rest means.
One clue is from v.10 that describes a characteristic of someone who has entered this rest. It is that he has 'rested from his works'. In this context, we know that man's strongest works are done to please God and to find acceptance from Him by doing whatever man thinks God demands of him. All religions of this world follow this path in one way or another. But the Bible tells us that it is not possible for anyone to qualify like this before God (Ro.3:20). All who follow this path are constantly in unrest because they can never know till they die if they have been accepted by God! God wants to give us rest here! By faith we can become justified before God through repentance and receiving His undeserved favour (Ep.2:8,9). Those who have experienced this salvation know the value of this rest!
Another way we get into unrest is by pursuing after love and recognition from people. What we get in this is never enough! We compromise our values in order to find acceptance from them and we try to impress them and get a name through wealth and achievements. But this makes us very insecure and robs our peace and sleep. This too can disappear if we give up such man-oriented ambitions and focus on just doing God's will for us, whether people recognise us or not.
For sincere disciples of Jesus, another area of unrest comes from finding that they are very different from Him in their behaviour and even thinking! We keep discovering in the situations of life that things come out from us that are dishonouring to our Lord (Ro.7:22,23). We ought to enter into rest in an increasing manner just like the people of Israel entering the Promised Land by overcoming the different Canaanites who used to live there, one by one. For example, shouldn't we be becoming less and less anxious about the future as we get to trust in God more? This way involves the process of sanctification that should be going on in a progressive manner all through our life.
What if we have not entered into this way of rest, even if we have considered ourselves 'good' Christians? God says that it is possible even now to enter into this path of rest (He.4:6,7). The most important thing is to have trust in God (v.3) and to become obedient to Him (3:18,19). We also need to be consistently diligent (labour - KJV) not only to enter this rest but also to remain in it (4:11).
By giving up trust in our good works to become pleasing to God but trusting in His grace, we can get rid of that huge unrest. Giving up seeking great things for ourselves and choosing to do God's will alone will bring great rest into our heart. As we trust God and begin to obey Him in all things, our rest will increase!