Shaytan uses the moments we are away from the dhikr of Allah to attack

he (ar-rajeem) uses:

Ghaflah - absent-mindedness, carelesness on our part.  Shaytan uses this to his advantage.

Shahwaah - personal desires, weaknesses.  Shaytan uses this to snatch at our eman.

Ghadhab - anger. Shaytan snatches it, and uses it to make the human being do wrong.

Adam, pure Adam, was taken in by shaytan in a moment of shahwaah and ghaflah.

Imam Shafii on his death bed:  Without You, Ya Allah, no one would be able to conquer Iblees.  How can one do that when he deceived your pure Adam?

But, there is TAWBAAH - repentance, to come back to Allah with a earnest heart and sincere intentions

Tawbaah strengthens an abd to such an extent that shaytan screams and regrets ever tempting the abd in the first place - because that abd returns to Allah stronger and more steadfast than ever before.  In that moment of awakening from ghaflah, the servants of Allah approach Allah with broken hearts, they feel unworthy, humble, shy, their sins ugly and dirty,  humiliated and ashamed in front of Allah; and with such profound sincerity, it bursts into tears and regret - this is the most desired state of spirituality.  Immediately they run to good, and increase their reserves of hassanah.  This eradicates themselves- they don't want what they want anymore- forget dunyaa, forget personal desires- they are mufliss- bankrupt begging in front of Allah for His forgiveness and mercy.

Sayyidul Istighfaar:  The Mother of Repentance duah:
Allahumma anta Rabi. La illaha illa anta. khalaqtani, wa anna alah ahdeeka wa wa'deeka masta'ta'.  audhubikka min sharril ma sana'tu. abu lakka bi ni'mitikaah alayya, wa abu u bi dhambi. Faghfirlee fa inna hu laa yaghfiru a dhunuuba illa anta.

Oh Allah You are my Lord. None has the right to be worshipped except You. You created me and I am Your servant, I abide by Your covenant and promise to the best of my ability. I seek refuge in You from the evil which I have committed.  I acknowledge Your favor upon me and I acknowledge my sin. so forgive me, for verily none can forgive sin except You.

Sometimes an abd will do a good deed and enter the Hell-fire because of it, and sometimes an abd will do a bad deed and enter paradise because of it.

Why?

An abd may do a good thing with an intention that is ugly, and he becomes arrogant, self-righteous, self-content because of it, and that good deed will lead him to Jahannum.

An abd may commit a sin, but turn to Allah in tawbaah, in a state of mufliss that will lead him to do so much that the sin will lead him to Jannah.

We need to guard ourselves not only before the action (niyyah- intention), during the action (i'tibaa- doing it right) but after.

Hadeeth:  Bad conduct corrupts good actions as vinegar spoils honey.

When Allah wants khayr for an individual he tries him with difficulty.  Allah then opens for the abd the 'flood gates' of tawbaah, that tawbaah leads him to feeling the insignificance of the self- which leads him to humility and humbleness- which leads him to Jannah.

When Allah wants someone to perish in his/her life, Allah leaves that person to rely on his/her nafs, (the typical secular humanistic philosophy, doing what feels right, this trust in self, that we know what's right and wrong, and we can rely on intelligence alone) this leads to feelings of arrogance and self reliance- moves he/she away from the teachings of Allah and the wahy - which leads him/her to Jahannum.

The shortest path to Allah is the path of an 'abd: al-ubudiyyah.The thickest of veils between an individual and allah: ad-da'waah(ad-da'waah: acts with Allah in arrogance, boastfulness, I deserve this) The closest gate from which one enters the presence of Allah is miflaas - bankruptcy of heart, humility, coming to Allah with NOTHING- my action, my words, are nothing- my account of deeds is nothing, empty.  With a heart that has been broken and humbled, so deep, not superficial, reached the core of the heart, the depths, and broke it- until I realize every aspect of my existence is totally and absolutely dependant on Allah-

How can I then not show shukr, show sabr, and not be oft-repentant?