بَلَى مَنْ أَسْلَمَ وَجْهَهُ لِلّهِ وَهُوَ مُحْسِنٌ فَلَهُ أَجْرُهُ عِندَ رَبِّهِ وَلاَ خَوْفٌ عَلَيْهِمْ وَلاَ هُمْ يَحْزَنُونَ
Translation: Nay, but whoever submits his face (himself) to Allah and he is a Muhsin then his reward is with his Lord (Allah), on such shall be no fear, nor shall they grieve. [Suratul Baqarah, verse 112]
1. Submit to Allah = fulfill the faraidh and abandon the haram
2. Be a Muhsin = do ibadah as if you see Allah, treat parents outstandingly, fulfill the rights of others outstandingly…basically, do good at every opportunity and whatever you do, try to be outstanding in it.
_1 + 2 = Reward is with Allah AND no worries in life (no fear nor any grief).
Why? Because you KNOW you did your best in the most outstanding way (ihsan, point 2), and you KNOW you are doing it for Allah (submission, point 1). So, no worries!