Will prayer and standing (in worship) be accepted without khushu' (devotional humility), even with the struggle of the self for it, and what is the means to achieve it?

Humility (khushū‘) is attained through striving (mujāhadah); whoever strives against his soul will attain guidance commensurate with his striving. Humility in prayer is like the soul in the body, and one's reward from prayer is proportional to the presence of the heart in it. The advice of the Salaf is to strive and not despair, and to increase in acts of obedience and in the means that aid in achieving humility.