सन्न्यासस्तु महाबाहो दुःखमाप्तुमयोगतः ।
योगयुक्तो मुनिर्ब्रह्म नचिरेणाधिगच्छति ।। ५.६ ।।

sannyāsas-tu mahā-bāho duḥkham-āptum-ayogataḥ |
yoga-yukto munir-brahma na-cireṇādhigacchati || 5.6 ||

Krishna has something more to say, quite relevantly. It is a clear guidance for ardent seekers and students. In a way, it is a timely information. But, it is also a caution, even a warning:

The path of sannyasa is very hard to adopt, without the strength and support of yoga. The seeker who is integrated through yogasadhana, attains before long, Brahman – the Supreme Reality.

Sannyasa is, no doubt, the natural culmination of spiritual wisdom and fullness. But it is not meant for everyone and all. The hold of prakrti (Nature) with its gunas is too strong to be set aside. The gunas are relentless in generating the impetus for sensory and bodily activities in all. To substitute these normal activities exclusively with sravana, manana and nididhyasana – the three-fold disciplines the Upanishads emphasize – is not feasible for all.

One must have the depth and strength of exclusive seeking or the undeniable benefit of age and the consequent withdrawal. Taking this into account, Krishna is quite emphatic that without the progressive purity and refinement, which active involvement brings about, exclusive renunciation is not feasible. To plunge into the exclusive wisdom pursuit will be to force self-denial, to invite disharmony and conflict.

On the other hand, if the seeker is patient and resolute to gain the benefit of yoga-pursuit and orientation, his emotional and intelligential propensities will get sublimated. Before long, he will be quite ripe to take up the wisdom pursuit, even exclusively, as Krishna alludes in the 18th chapter (18.50-53). To adopt the wisdom-path all of a sudden, disregarding the compulsions of Nature, will be to cause a grave violation and disharmony.