Your internal disposition affects your external actions, and your external actions affect your internal disposition. The second part is important.
Suppose you say something rude to your mother. You know that what you did is wrong, but you don’t feel moved to say “Sorry”. Say “sorry” anyway, not because you have a fuzzy feeling that compels you to do it, but because you know it’s the right thing to do.
Suppose you are in a mood where you have no desire whatsoever to say a prayer of thanksgiving to God. Say a pray of thanksgiving to God. Not because you feel stirred to give such a prayer, but because you know it’s a good & fitting thing to do.
Suppose you commit to saying the Rosary once a day, but you don’t feel moved to do it. Do it anyway. Not because you feel like doing it, but because you know it’s a good & fitting thing to do.
Suppose you have an anger towards someone. An anger that makes your blood pressure rise and your nails hungry for flesh. Say in your heart “I love you” to this person, not because you feel swayed to do it, but because you know it’s the right thing to do.
If you take sand paper and rub against the grains on a coarse plank of wood, and continue to sand it against the grain, eventually, the wood will become smooth. This is an endeavor that involves a lifetime commitment. The more you do it, the more habituated it will become for you. Keeping a journal with frequent examinations of conscious is very valuable towards this goal. Gradually, slowly, painfully, assuredly, your external actions will affect your interior disposition more and more.