“If you have made a rule to read so many prayers (whether they be long or short, fulfil the reading of all of them well), read the prayers with all conscientiousness, and do not do God’s work with your heart divided in two, so that only one half belongs to Him and the remaining half to your own flesh. God is a jealous God, and will not suffer your duplicity, your self-pity. .”
(St John of Kronstadt,  ‘My Life in Christ’)