To me, sadhana is a daily spiritual practice allowing time and space for an individual to turn inward.
As Yogi Bhajan (of the Kundalini yoga tradition) says, "Sadhana is self-enrichment. It is not something which is done to please somebody or to gain something. Sadhana is a personal process in which you bring out your best."
Sadhana could be taking a walk in nature, doing breath work or yoga asanas on a mat, spending time meditating or chanting, reading and reflecting on a poem, or simply watching the sun rise.
Please accept this post as a possible starting point for your own practice today.
Faith, by David Whyte, from Where Many Rivers Meet
I want to write about faith, about the way the moon rises over cold snow, night after night,
faithful even as it fades from fullness, slowly becoming that last curving and impossible sliver of light before the final darkness.
But I have no faith myself I refuse it even the smallest entry.
Let this then, my small poem, like a new moon, slender and barely open, be the first prayer that opens me to faith.