Fulfil your promises because you will be answerable to Allah for these promises!
Many of us have confined the issue of Iṣlāh and reformation to only our outward appearance, or maybe to the acts of ʿibadāt (worships). We come to our masjid, and perform our salāt, make some tilāwah of qur’ān, make some ẓikr, probably give some ṣadaqah and charity, wear a sunnah clothing and keep a beard. But with all that, the internal value of the human being is equally important. And that is our muʿāmalāt, our dealings with people, even in the outside world.