Krishna says (2.67) that the mind, which follows roving senses, carries away one's intellect as the wind carries away the boat on the water. The wind is a metaphor for our desires which drives our mind and senses making intellect (boat) unstable.
In the context of desires, life is divided into four stages namely Brahmacharya (bachelor), Grihast (householder), Vanaprastha (facing forest) and Sanyasa (renunciation) where division isn't just on age but also on the intensity of living.
The first stage includes growing up, gathering theoretical knowledge and physical strength along with some basic skills. In the second stage, it's family, work, refining skills, gathering possessions and memories, exposure to various facets of life and gaining life experiences through pursuing passions and desires either with success or failure. Through this process, one attains a cocktail of knowledge, skill and life experiences which is the breeding ground for awareness.
Transition to the third stage isn't automatic. As per legend, in the Mahabharat, King Yayathi took a thousand years for this transition as he couldn't leave his luxuries. Interestingly, these extra years came at the cost of a son. In these circumstances, this verse (2.67) helps us to reflect upon and make the transition to the third stage.
In the third stage, awareness lets us slowly drop desires as one realises that the desires of the past look silly or irrelevant now; how our assumptions were erroneous; how both fulfilled and unfulfilled desires can have the same disastrous consequences. With this realisation, one is ready for the final stage to become a sanyasi, which is dropping of ahankaar/kartapan (sense of doership) to be a sakshi (witness).
In the final stage, it's the transition from 'knowing' (through senses) of the first stage to 'being'(independent of senses). Krishna calls this (2.68) "Wisdom is established when all senses are restrained from sense objects."
Source - Daily World