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.
"In the Mushroom Summer," by David Mason
Colorado turns Kyoto in a shower, mist in the pines so thick the crows delight (or seem to), winging in obscurity. The ineffectual panic of a squirrel who chattered at my passing gave me pause to watch his Ponderosa come and go— long needles scratching cloud. I’d summited but knew it only by the wildflower meadow, the muted harebells, paintbrush, gentian, scattered among the locoweed and sage. Today my grief abated like water soaking underground, its scar a little path of twigs and needles winding ahead of me downhill to the next bend. Today I let the rain soak through my shirt and was unharmed.