There are two types of spiritual aspirants – those who work for an unselfish ideal but lack the vision to fix Enlightenment as the goal and the rare one who has the clarity to understand the futility of the world and works only to break free and reach Godhood. This verse speaks of the latter.
Such actions are the most powerful – neither casual, tamasika, nor involved, rajasika. Pure, sattvika action. They lead you to the home of learned yogis, spiritually evolved people. So it is your vasanas that determine your environment. You go to a situation that is most conducive for your further spiritual development.
Samskaras or the environment you are brought up in and the values you are exposed to in early childhood make a huge difference in moulding your personality.
When the environment is more suited to your spiritual growth and your vasana for Enlightenment is stronger you put in more effort and the journey gets smoother. You are able to focus better. Everything else falls into place. Otherwise, you waste a lot of time and effort in irrelevant issues.
This does not apply only in rebirth. Even in this lifetime, you can get second wind. If you invest all your thoughts in the spiritual field your environment changes and life becomes easy. The Bhagavad Gita revitalises you with enthusiasm, clarity and cheer. Then you are able to focus all your energies on getting to Realisation.