People make large resolutions at the new years, only to forget them a few weeks later. The Holy Quran tells us that even if we do an atom’s worth of good we will see a reward for it. So, if we make a small resolution and keep to it that is much more achievable and useful. We will benefit from it.
But a Muslim makes a resolution every time he prays and at the next prayer he checks how far he has succeeded in achieving what he resolved. So small changes which are possible are constantly reviewed are better.