Making Your Own Heaven (or Hell) Based on teachings of Rabbi Chaim of Volozhin
Nefesh Ha-Chayim Gate 1, Chapter 7
Man is referred to as the nefesh and the neshamah (soul) of multitudes of worlds. This does not mean a soul in the sense of a soul that is literally placed and attached within a person's body... Rather, just as a person's soul activates the movement of the body's limbs... so to the tendencies of the powers and the higher worlds and the order of the heavenly Chariot, their rectification (tikkun) or their destruction, God forbid, are all activated by the actions of man in the lowest world...
And this is because he is composed of and constructed from the supernal and lower powers and worlds... he incorporates all of them... Therefore man has been given the choice to direct himself and the worlds in whichever way he desires...
(יד) וַיֹּ֤אמֶר אֱלֹהִים֙ אֶל־מֹשֶׁ֔ה אֶֽהְיֶ֖ה אֲשֶׁ֣ר אֶֽהְיֶ֑ה וַיֹּ֗אמֶר כֹּ֤ה תֹאמַר֙ לִבְנֵ֣י יִשְׂרָאֵ֔ל אֶֽהְיֶ֖ה שְׁלָחַ֥נִי אֲלֵיכֶֽם׃
(14) And God said to Moses, “Ehyeh-Asher-Ehyeh.” He continued, “Thus shall you say to the Israelites, ‘Ehyeh sent me to you.’”
Nefesh Ha-Chayim Gate 1, Chapter 7 continued
This is as per the midrash: God instructed Moses to tell Israel that His Name is "I will be as I will be." What is the meaning of "I will be as I will be?" That just as you are with Me, so too I (God) will be with you.
(ה) יְהוָ֥ה שֹׁמְרֶ֑ךָ יְהוָ֥ה צִ֝לְּךָ֗ עַל־יַ֥ד יְמִינֶֽךָ׃

(5) The LORD is your guardian, the LORD is your protection (shadow) at your right hand.

Nefesh Ha-Chayim Gate 1, Chapter 7 continued
What is the meaning of "God is your shadow?" He is like your shadow. Just as with your shadow, if you play with it, it plays with you. If you cry, it cries, If you show it an angry or a hopeful face, it similarly gives you the same...
As per the Zohar: Come and see. The lowest world stands to continually receive... and the supernal world only gives according to the way he stands. If he stands with a shining face looking upwards from below, then for that reason he is enlightened from above. And if he stands in sadness, then he is given that same judgment in response. In this vein, the verse states (Ps. 100:2): "Serve God with joy," for a person's joy draws upon him a separate supernal joy.
Nefesh Ha-Chayim Gate 1, Chapter 10
An angel is certainly incomparably greater than a Jew in terms of his essence, the greatness of his holiness, the awesomeness of his perception. There is no comparison...
However, in one respect man has a distinct, significant advantage over an angel, in that he can elevate and interconnect the worlds, powers and lights with each other. No angel is capable of doing this at all...
The three levels of a man's soul -- Nefesh, Ruach and Neshama -- are only enabled to raise and interconnect the worlds and themselves when they descend to this physical world of action and are manifest within a man's body...
This is also the idea represented by the vision of the ladder in Jacob's dream. Refer to the Zohar: "'He breathed a living breath (soul) into his nostrils' (Genesis 2:7), about which it says, 'he dreamed and there was a ladder.' The ladder is certainly his living soul... It was through his ladder/soul that "and behold the angels of God were ascending and descending on it" (Genesis 28:12)... This means this ascending and descending of the angels happens through man's living soul... with its lowest end being manifest within man's body.
(יא) כִּ֤י פֹ֣עַל אָ֭דָם יְשַׁלֶּם־ל֑וֹ וּֽכְאֹ֥רַח אִ֝֗ישׁ יַמְצִאֶֽנּוּ׃
(11) For He pays a man according to his actions, And provides for him according to his conduct;
Nefesh Ha-Chayim Gate 1, Chapter 12
From the moment it enters into a person's thought to perform a mitzvah, immediately it makes an impression Above, in his supernal source... The impression Above inevitably also arouses and draws down an enveloping light upon him from the Supernal Holiness, which assists him to complete the mitzvah. On completion of the mitzvah, this holiness and lighht returns to its source...
This is the concept of reward in the future world, which is a person's actual actions, which after the separation of the soul from the body, his soul ascends to enjoy and be sustained by the subtle shining of the holy lights, powers and worlds, which have been added to and increased by his good deeds...
This is as Chazal state: "All Israel has a portion to the World to Come." They do not say the portion is in the World to Come, as this would imply that the World to Come already existed at the time of creation as an entity in its own right, and if a person would deserve to receive it, he would be rewarded by being given a part of it.
However, in reality, the World to Come is generated by a person's actual actions, whereby he extends, adds to, and rectifies (hitkin) his own portion through his own deeds... Therefore Chazal say that each individual Jew has the portion of holiness, light and subtle shining that he himself rectified and added to in the World to Come from his good deeds.
Nefesh Ha-Chayim Gate 1, Chapter 12 continued
Similarly, the punishment of Gehinnom is the same idea, that the sin itself is the person's punishment... When a person [sins] the damage and destruction, God forbid, makes an immediate impression above in his source...
[Suffering for our sins] is not out of punishment or vengeance, God forbid, but rather "Evil pursues sinners" (Proverbs 13:21). It is the very act of sin which is the punishment in and of itself... For since the Creation, God has established the natural order of the behavior of the worlds, that they are dependent upon the level of arousal of man's actions -- whether good or bad, God forbid -- that the actions of each individual automatically impact his source and root.