As-Salaam alaikum,
Sometimes we tend to think that only a few big sins like theft, robbery, adultery or fornication are actual sins, and that not falling into them make us a muttaqi. But if the reality of taqwa truly dawned on us, we would seek Allah's forgiveness for even the good we have done; in that: 'O Lord, what worth is there in our good deed? We don't ask a reward for it; instead, please forgive us.'

Without rooting this reality in our soul, that any good we do has its true source in Allah Ta'ala, we will be in danger of falling into ujub: vanity and self-conceit. Ujb is when we fail to realize the good we have done is not of our own doing: it is a gift from Allah. Only when blinded to this do we then see good deeds as being of our own achievement. It is here we begin to become vain or egotistical, basking in our own self-glory. Beware!!