Dua to be recited when any work becomes difficult

اَللّٰهُمَّ لاَ سَهْلَ اِلاَّ مَا جَعَلْتَهُ سَهْلاً وَاَنْتَ تَجْعَلُ الْحَزَنَ سَهْلاً اِذَا شِئْتَ

O Allah! No work is easy except that which You make easy, and when You are able to soften the rocky ground when you wish.

(Al Hisnul Haseen pg.194)