"Abhyasa is a disciplined, persistent effort to remain focused. This focus can occur during physical exercise (such as asana), breath work (pranayama), meditation (samyama)... Abhyasa is the effort required to maintain a focus, and it is to be done continuously over a long period of time, with sincerity and care. Abhyasa involves a committed effort to maintain your chosen practice long enough to reap its award. Abhyasa along with Viveka (keen discernment) is a primary practice that is fundamental to all progress. Abhyasa along with not clinging to external objects (vairagya) is necessary to calm the mind-heart... Consistent and persistent effort, along with the ability to not let external events throw us off center, is bound to diminish the thoughts and emotions distracting our heart-mind."
The Path of the Yoga Sutras by Nicolai Bachman