Each week in class it is likely that you will encounter poses or movements that are very difficult for your body at this time. Try not to feel despondent. These are only some of the thousands of yoga poses. They are to be approached with playfulness and curiosity.
Often adjustments and modifications make these movements more accessible. Sometimes some asanas do not suit us.
At these times we need to be very mindful and notice whether our egos are pushing us further than is right for us, or whether we are moving in harmony with the needs of our body.
Over time, especially if we practice regularly, many movements become easier as our strength, flexibility, balance and mindfulness develops. Sometimes we have disease processes or injuries which affect us, so we need to be extra receptive to what our bodies need. This may mean adjusting, doing an alternative movement or resting as needed.
In yoga we are aiming to find that balance between effort and comfort, and to find steadiness of body and mind. In the ancient Patanjali's Yoga sutras this is referred to as Sthira and sukha.
Sthira is the ability to “hold steady” in an asana, to hold the body, our energy, and mind in balance for an extended period. This capacity is known as asana sthiti, which can be translated as either “dwelling in an asana” or “steadfastness in an asana.” True asana sthiti arises when the muscles are evenly engaged and free of tension and strain; when the cadence of the breath becomes rhythmic; and when the mind becomes patient and vigilant, observing whatever arises from moment to moment.
Sukha, or “good space,” in asana practice is the comfort that arises when the joints and bones are harmoniously aligned with gravity and when the muscles are free of strain. At the energetic level, sukha manifests as an easy flow of breath and balanced circulation of prana (life force).
I hope that you find that working to find sthira and sukha, together with slow mindful breathing, helps us all to find this “good space,” which manifests as a meditative quality of joy, satisfaction, and spacious awareness. I hope that you then leave class feeling relaxed, energised and positive.
Reference: https://yogainternational.com/article/view/sthira-and-sukha-steadiness-and-ease/