As‘salaamu alaikum. Like Medi1Saif I wonder what the brother means by “thinking about Allah”, because there are different ways of thinking about Allah.
If the brother means “thinking about” as in “trying to figure Allah out so as to comprehend Him” then he is in obvious error. In 6:103 Allah says, “No vision can grasp Him, but His grasp is over all vision. HE IS ABOVE ALL COMPREHENSION, yet is acquainted with all things”.
Now if the brother means “thinking about” as in “trying to attain a greater appreciation of, or a deeper affection for Allah” then that is the kind of “thinking” that will bear him good fruit.
I personally like to think about Allah in His capacity of Al-Wadood (the Source of Love), remembering the hadith wherein the Prophet (a.s.) told his Companions (r.a.) that Allah loves us more than a mother bird loves her babies. I always experience a profound affection towards Allah swelling in my chest from this line of thinking. During some of the saddest and most difficult times in my life I have been consoled by that thinking.
I think that we sometimes get so lost in the intellectual aspects of Islam that we forget that the practice of the Deen is supposed to provide us with positive EMOTIONAL experiences and nurturing as well. This is never more true when it comes to thinking about Allah, (keeping in mind that tasbih, tah‘mid, takbir, and all other types of dhikr are just different forms of thinking about Allah).
“But the believers are overwhelming in their love for Allah.” Qur‘an 2:165
“...And celebrate the praises of your Lord before the rising of the sun and before its setting; yes, celebrate them for part hours of the night, and at the sides of the day, THAT YOU MAY HAVE JOY AND PLEASURE.” Qur‘an 20:130
“For the believers are those who, when Allah is mentioned, feel a tremor of fear in their hearts...” Qur‘an 8:2
“Those who believe and whose hearts find satisfaction (tranquility, or rest) in the dhikr of Allah, for, without doubt, in the dhikr of Allah do hearts find satisfaction (tranquility, or rest).” Qur‘an 13:28