While doing fardh ibadah like Salah, Fasting etc. 'Articulate' the niyyah in your heart. Say the actual words of niyyah in the heart without voice or moving the mouth. Eg: 'I am praying 4 rakats of Fard Asr Prayer facing Qibla for Allah Ta'ala', 'I m fasting tommorrows Fardh Fast of Ramadan for Allah Ta'ala'.