Sannyasa, or “renunciation,” is often portrayed as a holy life free of duties and responsibilities in order to focus on the ultimate objective—moksha (liberation). Traditionally, sannyasa is the monk’s lifestyle, one in which worldly objects and relationships are given up, and poverty and chastity are the accepted rule. However, there’s more to it, and just putting on orange robes doesn't make one a sannyasi.
There are two kinds of sannyasa. The first one, vidvat-sannyāsa, is about becoming a renunciate after knowing and assimilating the truth. As a result of Self-inquiry, the wise (jñanis) have given up wrong ideas about their identity. They have cognitively resolved erroneous concepts they had about the world and who/what they are. In the case of vidvat-sannyasa, there is no sannyasa to be taken. Vidvat-sannyasa requires no outward modifications to one’s mode of living, because it’s simply a byproduct of realizing and actualizing the Self. It’s said that vidvat-sannyasa is the culmination of someone having lived through all of life’s stages, gaining and actualizing the right knowledge, and fulfilling their human purpose.
Vividisha-sannyasa (vividiṣā-sannyāsa), on the other hand, is what’s more commonly known as “putting on the robes” or “taking sannyasa.” It includes a formal lifestyle commitment to the pursuit and obtainment of Self-knowledge, and in doing so, a foregoing of relationships and outside interests. Vividisha means “desire to know.” This is the austere lifestyle of monks and nuns who become a renunciate before knowing and assimilating the truth. Vividisha sannyasis are free of duties and social obligations, and dependent on those, for their basic needs, who value their dedication to gaining and disseminating the truth. In this way, it is very much a community-supported sannyasa. Nevertheless, both vidvat- and vividisha-sannyasa are marked by fearlessness, detachment, and a seeking of the truth. Both may also include service, usually in the form of teaching.
In the Bhagavad Gita, Arjuna is confused about the difference between being a sannyasa (the seeking of moksha, absent of worldly activities) and karma yoga (the seeking of moksha, while still involved in the world). After hearing Krishna espouse the renunciation of action through knowledge of the Self, Arjuna has doubts about which path he should take. Krishna tries to convince him that he has worldly responsibilities to tend to—namely, an army to lead and a war to win!—and that it’s no time for him to be shirking his duties and run away to live in solitude.
Furthermore, Krishna makes it known that both renunciation of action (sannyasa) and performance of action (karma yoga) lead to the same goal. Thus, it’s not a question of one path being better than the other, but which lifestyle best fits the temperament of the seeker. Few have what’s required to suddenly become a complete renunciate. In addition, becoming a renunciate and renouncing one's conditioning isn’t as easy as it looks (more about that later).
In the Gita, Arjuna’s life up until now has mostly been about one conflict after another, and he’s ready to throw in the towel. However, sannyasa as a means of escaping life doesn’t work due to those two pesky attributes, fear and desire. Out of fear, one might wish to escape worldly action, and out of desire one might wish to leave all their troubles behind. The problem is that fear and desire are the antithesis to a life of renunciation (whose goal is freedom from fear and desire). No one successfully maintains sannyasa under the spell of fear and/or desire.
Also, it would be naive to say that sannyasa equates to living without any difficulty. For a select few, vividisha-sannyasa comes natural because it matches their disposition in life. They already have a profound dispassion for the world and aren’t so easily swayed by bright, shiny objects. They still have vasanas (conditioned habits), but they are manageable. For most of us, however, a life without action would only lead to utter frustration. Truth be told, involvement in the day-to-day grind of worldly life has an important role in one’s spiritual development by providing an arena where one can express themselves and learn through their actions. In the field of experience, we are able to exhaust our likes and dislikes, and realize that all objects, experiences and relationships are empty of intrinsic and lasting value.
Arjuna, perhaps, mistakingly believes that by evading his duties and avoiding all worldly action, he will become an authentic seeker of the truth. But just because one abstains from a certain action, doesn’t mean they have complete dispassion for it. Vedanta teacher, Swami Dayananda draws this distinction by giving an anecdote about a boy who likes to play marbles. One day, a father tells his son he’s too old to be playing marbles and should instead, play cricket with the older boys. The son agrees, gives his marbles to his younger brother, and in fear of being tempted, avoids the places where the other boys play marbles. Dayananda explains that in this case, the boy’s giving up marbles isn’t actual sannyasa, because he only gives up playing marbles out of pride (“I'm grown up. Playing marbles is for babies.”). However, in reality, he could probably easily be talked back into playing marbles again! On the other hand, if we ask the same individual ten years later if he still has any interest in playing marbles, the answer will most likely be an unequivocal, “No.” The man—who was once a boy who liked playing marbles—has no sense of loss. The equivalent in Western culture might be a grown woman who no longer playing with Barbies. At some point in her life, playing with Barbies no longer has the same appeal. Dayananda tells us, “Having outgrown the fascination for childhood games, you are a marble-sannyasi. If the entire world holds for you no more attraction than those marbles—if your heart has found that fullness and maturity—you are truly a sannyasi.”
The conclusion is that real sannyasa cannot be chosen or taken, only discovered—usually through a long process of removing doubts and “outgrowing our fascination” for the world. Only by discovering and sustaining the thought "I am whole, complete, and totally free from dependence on objects, experiences and relationships for happiness," can we be a true sannyasi. It doesn’t mean we no longer gather pleasure from the world, just that we are no longer under its spell. Objects (including this body and mind), events and relationships are viewed as dream-like, passing entities. Any pleasure derived from them is known to be momentary and not something one can depend on. That said, one cannot will themselves to be a sannyasi—it must happen in its own sweet time—but it can be cultivated. How? By composing our thoughts with the right attitude (karma yoga), purifying them using meditation (ashtanga yoga), and then gaining knowledge of the Self using Vedanta. A little grace also helps!
Swami Dayananda has the last word on the topic when he says:
You have to wait for it to happen, while performing actions with the right attitude. This world has everything you need to bloom into a flower of maturity. A composed mind, the results of a life of karma yoga, will find sannyasa naturally…One who knows the Self that is actionless knows that I, Awareness, bless the mind that directs the sense organs and organs of action to act. I, Awareness, never performs any action. This person is a ‘sannyasi’. To gain this knowledge, one must discover a contemplative mind, and for that karma [action] is necessary. So get ready for action, O Arjuna, and act with the right attitude. [“The Teaching of the Bhagavad Gita,” pp.72-75, Orient Paperbacks]