What are the reasons that make prayer feel burdensome to the soul, accompanied by a sense of boredom, distress, and laziness, and how can one get rid of these feelings to achieve devotion (khushu') and experience the beauty of worship?

You must pray to God to help you overcome laziness and change your behavior patterns. As for the sweetness of worship, it comes with patience and perseverance, so strive against yourself in obedience, and you will be rewarded for this striving. As for humility (khushu'), be diligent in seeking its causes, and know that it is not a condition for the validity of prayer. Your prayer is valid even if some humility is lost. As for prayers intentionally abandoned, there is a difference of opinion regarding the obligation to make them up.