In Hindu traditional society, a yoga practitioner is meant to vary the practices he does according to the stage of life he’s in. We modern yogis would do well to consider such a template for living, as it would help us cover the bases for optimum spiritual development.
The four stages are called ashrama* in  Sanskrit, and they are: brahmacharya, grihastha, vanaprastha, and sannyasa.
The first stage includes youth/students from ages 8 to 25 years. This is when one is growing up and assimilating knowledge and values. Yoga practice is energetic, mainly physical, but still with a small emphasis on pranayama and meditation.
Next is the householder stage from ages 25 to 50 years, when one focuses on marriage, family, vocation, and civic responsibilities. While this is still a busy time of life, the yoga practitioner balances physical and reflective practices equally.
Then there’s the retirement stage around middle age and later. This is when one’s children are grown, but now there may be grandchildren. The demands of work may have decreased or stopped and one finally has time to be more inward. One is free to reflect on what lies beyond the mundane life. Rather than emphasising physical practice, there’s a tendency to be more introspective, doing pranayama, meditation, and studying ‘wisdom literature’.
Lastly, there’s the renunciate stage that is usually associated with old age (Actually, this stage can be entered into at any age.) In India one is sometimes called a Sadhu or a Sannyasin and gives up family attachments and withdraws from society. The forest or cave dweller is the stereotype of this individual. In our society, we see individuals doing long and mostly silent retreats.
The value of adopting this traditional view is that it allows for the gradual development of a rich inner life and a movement away from the worldly towards a more spiritual existence.
Instead of ending up at the finish of life and wondering ‘Is this all there is?’ or ‘What was that all about?’, one has the necessary tools to face what might be the most challenging stage of life – and even embrace it.

Te samadhavupasarga vyutthane siddhayah

For an individual who may revert to a state of distraction, this extraordinary knowledge and the capabilities acquired through samyama are worth possessing. But for one who seeks nothing less than a sustained state of Yoga the results of samyama are obstacles in themselves.**
**Patanjali’s Yogasutras, translation and commentary by T.K.V. Desikachar.
*Not to be confused with the notion of a community of like-minded individuals.