Invocation for when you find something becoming difficult for you

((اللَّهُمَّ لاَ سَهْلَ إِلاَّ مَا جَعَلْتَهُ سَهْلاً، وَأَنْتَ تَجْعَلُ الْحَزْنَ إِذَا شِئْتَ سَهْلاً)).

(O Allah, there is no ease except in that which You have made easy, and You make the difficulty, if You wish, easy.)