All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
The term that expresses what you described of not doing what you intended to do or doing what you intended not to do is Al-Qadhaa’ wa Al-Qadar (Divine Decree and Destiny, or the Will and Decree of Allah). What you intended to do and then did not do is all by the Will and Decree of Allah; and what you intended not to do but then did is all by the Will and Decree of Allah. Both the action and non-action were predetermined by Allah.
Taawoos said, "I found some of the Companions of the Messenger of Allah, sallallaahu ‘alayhi wa sallam, saying, 'There is a measure for everything.'" Taawoos added, "And I heard ʻAbdullah ibn ʻUmar, may Allah be pleased with them, say that the Messenger of Allah, sallallaahu ‘alayhi wa sallam, said, 'There is a measure for everything, even ability (resolve/vitality) and inability (deficiency/lack of resolve).'" [Muslim]
An-Nawawi commented on the hadith, saying, "Ability is the opposite of inability; it is the vitality and cleverness with matters. It means that the lack of resolve of the incompetent person is predetermined and the vitality of the capable person is predetermined..."
Al-Haafith Ibn Hajar said, "It means that nothing takes place in the universe except with the decree, knowledge, and will of Allah. All things are predestined and decreed by His knowledge and will. The hadith highlighted the person's ability and inability as such in order to indicate the fact that although our actions are known to us and intended by us, they do not come to pass except with the decree and will of Allah..." [Fat-h Al-Baari]
As for your other question, "Is it proper that one should always think of Allah?" You should know that it is more appropriate to think about the blessings of Allah and His magnificent creation instead of thinking about His Essence. Ibn ʻUmar, may Allah be pleased with him, reported that the Prophet, sallallaahu ‘alayhi wa sallam, said, "Contemplate the bounties of Allah, and do not contemplate Allah." [At-Tabaraani; Al-Albaani: good] Another version of the hadith reads, "Contemplate the creation of Allah, and do not contemplate Allah." It means think about the favors of Allah upon you, and do not think about His essence, for whatever comes to your mind in this regard, He is unlike it.
Allah knows best.