How can one get rid of some personal problems, such as forgetfulness, lack of focus, laziness, and neglect, which trouble the inquirer despite his success in his professional and family life?

You should thank Allah for the blessing of Islam, health, well-being, and your professional and family success. Contentment with what Allah has ordained brings peace to the soul and dispels fear and sorrow. Be confident that the matters you mentioned are treatable with genuine desire and the right means, the greatest of which is supplication. Also, frequently memorizing the Qur'an to improve memory, and abandoning excessive looking, listening, speaking, eating, and sleeping, as well as abstaining from unlawful things. There is no harm in seeking assistance from educational and administrative books to learn organizational skills, decision-making, and how to deal with people.