Your word should outlast your mood.

Moods are weather and promises are structures, and the trouble starts when the weather gets a vote on whether the structure stands. You agreed to something while feeling one way, you feel another way now, and the new feeling argues convincingly that the agreement no longer applies. Nothing about the other person’s situation has changed. Only your enthusiasm has.

Split the two apart out loud: say you do not feel like it and that you are coming anyway. That sentence is allowed, and it is honest. If you notice you only keep the promises you still enjoy, start making fewer and heavier ones.