The Medrash Tanchuma Pekudai 3 writes that for nine months the fetus in its mother's womb has a candle above his head, a malach teaching him Torah, and he can see from one end of the world to the other. Before he is born a malach takes him to Gan Eden and shows him tzadikim sitting and learning Torah surrounded with kovid and with crowns on their heads. The malach then says if you will merit and keep the Torah of Hashem then you will also share in the same reward and sit amongst them.
Chazal go even further to say that every Yid already "experienced" living in Gan Eden. Hashem created Adam Harishon and placed him in Gan Eden. Residing in Adam Harishon were all the neshamos of Am Yisrael. The nefashos of goyim were created and entered Adam only after the chait of the Aitz Hadaas. We see from this that all Yisrael encountered and experienced Gan Eden not only for one day but according to some Chazal for the entire Shabbos that followed. This was to "wet our appetites" to possess an innate yearning to return to such a holy place in order to bask and delight in the radiance of the Shechinah.
After Adam was divorced from Gan Eden, and as a newborn after leaving our mother's womb, it would appear that another encounter in Gan Eden is out of reach. Not so writes the Sfas Emes Bereishis תרס"א -וכתיב ויגרש את האדם וישכן כו' את הכרובים כו' וכי צריך הקב"ה עצות לשמור שלא יכנסו בו. אבל מקרא זה בא ללמד כי הניח פתח לכנוס בג"ע מי שראוי רק יש בו שמירה
Subsequent Adam's expulsion from Gan Eden Hashem set up a security service that would ensure that no one even Adam, could reenter. Hashem stationed angels of destruction and the flame of the revolving sword to guard the way to the Aitz Hachayim. The Sfas Emes asks did Hashem really need guards to restrain people from entering the Gan Eden. The fact that he set up guards conveys that an individual who is truly worthy of experiencing intimacy with the Shechinah will somehow find a way how to reenter. Guards are for those people who are not righteous enough to do so.
Furthermore, even though one who is alive and has not yet achieved the caliber to physically enter Gan Eden, in many instances through his life he has the ability to experience Gan Eden spiritually. One of those examples is Shabbos. As the above Sfas Emes writes ולכן ביום שבת קודש דכתיב (יחזקאל מו א) "שער החצר הפנימית (רמז לגן עדן) הפונה קדים יהיה סגור ששת ימי המעשה וביום השבת יפתח" ובגן כתוב (בראשית ב ח) מקדם, שנפתח בשבת פתח והארה מגן עדן
Concerning Shabbos it is written that the gate to the inner courtyard which turns to the east although it is closed during the week opens up on Shabbos. The inner courtyard is referring to Gan Eden and on Shabbos one can receive part of its light. In describing Gan Eden the Torah uses the word קדים east and the gate that opens up on Shabbos although closed during the week is also called קדים. Understandably one must make himself a worthy vessel in order to experience this scenario.
The Nefesh Hachayim writes that every time one fulfills a mitzvah it is possible to be enveloped by Gan Eden if he merits so שער א ז. וכאשר ישים אליו לבו בעת עשיית המצוה יבין וירגיש בנפשו שהוא מסובב ומלובש כעת בהקדושה ורוח נכון נתחדש בקרבו וזה שאמר הכתוב אלה המצוות אשר יעשה אותם האדם וחי בהם, "בהם" היינו בתוכם ממש שהוא מסובב אז בקדושת המצוה ומוקף מאוירא דג"ע.
If a person when fulfilling a mitzvah will focus and concentrate his heart focus on his action, he will understand and feel in his nefesh that he is surrounded and clothed at this very time with a holiness and that a upright spirit was renewed in him. To this concept the passuk refers to אשר יעשה אותם האדם וחי בהם that when fulfilling mitzvos he will receive a spiritual life energy in "them" as if he is enveloped and embraced with their kedusha and their spiritual atmosphere of Gan Eden.
Interestingly the gematriah of בהם when spelled with the inner letters בי"ת ה"ה מ"ם equals 502 which is the total years of all three Avos. Avraham lived 175 years, Yitzchak 180 and Yaakov 147 altogether 502. They lived a life of kedusha and were enveloped with life energy from the mitzvos. This concept aligns itself with the Chazal in Baba Basra 17
ג' הטעימן עולם הבא בעולם הזה אברהם יצחק ויעקב כמ"ש בכל מכל כל Three people experienced Olam Habah in Olam Hazeh, Avraham Yitzchak and Yaakov. They lived a בהם" life" being a chariot for the Shechinah. When Yaakov Avinu came into Yitzchak to receive the berachos the passuk says וירח את ריח בגדיו and Chazal say (Rashi) נכנסה עמו ריח של גן עדן he was enveloped by the scent of Gan Eden. Yitzchak who was also on a high madraigah was able to smell the scent of Gan Eden enter.
Every day when one fulfills the mitzvah of wearing a Talis, the siddur has a supplication to be said before one wraps himself with it.
וכשם אני מתכסה בטלית בעולם הזה כך אזכה לחלוקא דרבנן ולטלית נאה לעולם הבא בגן עדן The Zohar writes from all the mitzvos we fulfill in this world a levush a spiritual clothing is created for the neshama. Just as one wraps his body with the Talit, so too his neshama is wrapped with the light and radiance of the mitzvah which is compared to spiritual clothing עוטה אור כשלמה. One's neshama also possesses 248 spiritual limbs and 365 sinews. In fact one should have intent in his beracha להתעטף over the tzitzis to include not only his body being wrapped but also his neshama. The light of the mitzvah which is the spiritual garment he experiences now in a physical body, will be waiting for him to wear in Gan Eden with an enhanced intense pleasure of a "zillion" plus times more because the neshama will be then without a body.
The Nefesh Hachayim writes in his sefer Ruach Chaim on Pirkei Avos- "As soon as an individual thinks about fulfilling a mitzvah he makes an impression in the heavens and a surrounding light of kedusha descends and encompasses him and he is in the middle. This light helps him complete the mitzvah. It is as if he is sitting in Gan Eden mamesh a holy place and the kedusha clothes him. When one finishes the mitzvah his clothes of light and holiness become even greater. This light and spiritual garments then ascend to shamayim to Gan Eden and they will be his future reward".
Every day when we fulfill a mitzvah we connect with the Gan Eden. The sefarim explain that this is the intention of Chazal when they say שכר מצוה מצוה (Avos 4,2). The reward for a mitzvah is all in the mitzvah itself. One's neshamah will be surrounded in Gan Eden with the light of the mitzvah which formed one's spiritual clothing to wear in Gan Eden. The more mitzvos fulfilled the greater the reward in Gan Eden.
From here we see that it is not that tzadikim will dwell in Gan Eden to receive their reward but rather it is Gan Eden which dwells inside and by the tzaddikim.
HAPPY ENCOUNTERS!