I recite a lot of dhikr and words that were narrated from the Prophet (blessings and peace of Allah be upon him), repeating the words verbally when my heart is distracted with other things. Do I have to think about what I am saying every time I recite this dhikr?
Praise be to Allah.
What is prescribed is to focus on the meaning of the words one is uttering so that one may attain the benefit of dhikr (remembering Allah). Therefore you should strive to reflect upon what you are saying when you recite dhikr. Then if the heart becomes distracted sometimes, there is no blame on you, in sha Allah. It is advised to seek refuge a great deal with Allah from the Shaytaan when you experience waswasah (whispers from the Shaytaan; compulsive thoughts).
And Allah is the source of strength. May Allah send blessings and peace upon our Prophet Muhammad and his family and companions.