That's like asking, how do we strive to enter into perfection, by simply practicing perfection. You strive with your might to rest here upon this earth upon God's Sabbath, and that you may rest in heaven with God and His creation. Sabbath means rest. You preform your works, then "Sabbath", or rest as God did from His works. He that has entered into God's Sabbath, rest, has ceased from his own works, as God did from His. Were not the works finished in creation week? Did not God then set the very day He rested then as special? Does not He call the Sabbath His rest? Did He not swear in His wrath that those who did not believe would not enter into His Sabbath? In Creation week, He rested with the works He had created. See God's joy and happiness, resting with His creation after creating them? See His joy and happiness, with all that was very good? And now, though in a marred creation, we may still come upon the very seventh day that He set apart and keep His rest. God's rest IS His Sabbath. Therefore, the Sabbath is the sign between Him and His people, between Him and His Creation. It is the sign that He is the Lord God, Who sanctifies us. Those sanctified people shall rest with Him in eternity, from Sabbath to Sabbath. Not those who do not believe, but those who believe. It is those who believe that keep His Rest. Not those who do not believe. Anyone can rest upon the seventh day. But not anyone can keep the Sabbath. Only those who truly delight in the LORD can keep the Sabbath, for their delight is resting with Him, worshiping Him, praising Him. They keep the Sabbath with joy in their hearts, and not as a meaningless round of ceremonies. They truly keep it holy, as He demanded. The memorial of creation, made for man, that man may be blessed. The memorial that remaineth, as Hebrews 4:9 says.justaname said:1 Therefore, while the promise of entering his rest still stands, let us fear lest any of you should seem to have failed to reach it.
2 For good news came to us just as to them, but the message they heard did not benefit them, because they were not united by faith with those who listened.
3 For we who have believed enter that rest, as he has said, "As I swore in my wrath, 'They shall not enter my rest,'" although his works were finished from the foundation of the world.
4 For he has somewhere spoken of the seventh day in this way: "And God rested on the seventh day from all his works."
5 And again in this passage he said, "They shall not enter my rest."
6 Since therefore it remains for some to enter it, and those who formerly received the good news failed to enter because of disobedience,
7 again he appoints a certain day, "Today," saying through David so long afterward, in the words already quoted, "Today, if you hear his voice, do not harden your hearts."
8 For if Joshua had given them rest, God would not have spoken of another day later on.
9 So then, there remains a Sabbath rest for the people of God,
10 for whoever has entered God's rest has also rested from his works as God did from his.
11 Let us therefore strive to enter that rest, so that no one may fall by the same sort of disobedience.
12 For the word of God is living and active, sharper than any two-edged sword, piercing to the division of soul and of spirit, of joints and of marrow, and discerning the thoughts and intentions of the heart.
13 And no creature is hidden from his sight, but all are naked and exposed to the eyes of him to whom we must give account.
Hebrews 4:1-13
Here now is the complete context of the verse...
How are we to strive to enter the rest if it is simply observing the Shabbat?
Here is the key verse in interpreting this particular periscope.
for whoever has entered God's rest has also rested from his works as God did from his. Hebrews 4:10
It remains from Eden. It remains from the law. It remains now. And it shall remain forever. It remaineth.