Make promises cautiously and fulfillment routinely.

Most reliability problems begin at the promising stage rather than the doing stage. Commitments are made quickly, generously, in a moment of goodwill, and then have to be carried by a future self with a full calendar. Slowing down the promising fixes most of it.

Build in a pause before agreeing to things. Check the calendar, not the mood. Fewer commitments delivered completely will serve you and everyone else better than many delivered partly.