To become a Sannyasi of ISKCON, not much penance is required. Only some rules written in the scriptures have to be followed.
Before becoming an ISKCON Sannyasi, you have to live in the temple of ISKCON for a few years as a celibate. A sannyasi will guide you during this period, he will be your education guru. But before becoming a brahmachari, it is necessary for you to complete the Cosmic Education of the material world.
Spiritual progress in ISKCON
Your spiritual progress will continue with the highest guidance of the Spiritual Guru. In this period, it is necessary to wear a dhoti kurta of yellow fabric. By taking the guidance of such Spiritual Gurus, positive changes will start taking place in you. Krishna devotion and Krishna service will be your work in ISKCON.
After two years you will be given a white colored dress, a dhoti, and a kurta. This is a sign of your progress. As a sannyasi, you will continue to have many Courses. During this period, you will be given the responsibility of serving in the temple, kitchen, or distribution of Offering (Prasad) outside. During this period, you can do bhajan Sankirtana, instrumental playing, singing, cooking, and Sanskrit language courses according to your wish in the temple itself.
Rule for Sannyasi
After following the first four preparatory rules of ISKCON which are giving up meat, sex, gambling, tea, and coffee, your observance of celibacy is mandatory. As well as you can only consume Offering (Prasad) made without Garlic and Onion.
After that, It is mandatory for you to give up all kinds of electronic devices. You will have a simple mobile with a button and a NEW SIM card will be given to you. After this, it is mandatory for you to listen only to God’s (Krishna) Music, kirtans, and Bhajans.
During the Brahmachari period, you cannot go anywhere without the permission of your Guiding Education Guru. Your every work will have to be done according to the permission of your Education Guru. After this, the education guru selects whether you are eligible to take Initiation or Not.
When you will be selected by your education Guru, then the head Guru of ISKCON will give you initiation of Sannyast. And with initiation, you will get a new name which is like Gopinath Das, Madhusudan Das, (like Radhanath Swami Maharaj, Loknath Swami Maharaj…). Now it is mandatory for you to go and stay Where and in which city they will decide your service. Then whether it is in Pakistan or America or in any city temple in India. Now that you have become devoted to God, your path will now be decided by the Guru. And now it will be mandatory for you to wear saffron-colored clothes.
After becoming a Sannyasi you will do a great job of spreading the Bhagwat Gita in the world, taking classes to make people understand the Gita, bringing great knowledge of Shrimad Bhagavatam to the people, giving proper guidance to common people on life, and spreading Krishna devotion. Sannyasis do a great job of spreading Krishna Bhakti.