Chaurasi lakh joon
The Chaurasi Lakh Joon refers to the 8,400,000 lifetimes/lifeforms that exist on the Planet Earth as viewed by Sikhs, 4.2 million of which are on land and the same number in water.
After entering the Chaurasi Lakh Joon, there is no actual way to come out. It could take years and years to complete this cycle. Once the cycle is complete, one gets a chance to become human again and release themselves from this world by chanting "Waheguru" (God's name) repeatedly. Some believe that for Sikhs, there is one way to make sure one will not enter the cycle, and that is performing the Japji Sahib paath 84 times on each one of the steps at the Shri Baoli Sahib Goindwal Sahib.
This only releases you from the cycle and not the world. In other words, this gives you another birth as a human after you die. Every year, millions and millions of Sikhs visit this Holy Shrine, some of which are there to take a bath in the holy waters of the well, and others which are there to release themselves from the cycle and give themselves another chance if they do not release themselves from the world in their current birth.
It is a good experience but indeed very tough. Not as tough as the Chaurasi Lakh Joon, though. It is recommended to everyone and there are barely no requirements except for knowledge of the Japji Sahib paath.