It only matters if you let it.
Life gets busy. A day slips by, and as you drift off to sleep, you remember your promise to do the work.
You've forgotten by the time you wake up the next day, and another day slips by.
Pretty soon, a week has passed, and you haven't done what you promised yourself to do.
We all forget.
The goal is not to blame yourself. Accept the mistake and try again the time you remember.
Bonus tip: if you've built a practice on doing something for one minute, start there when you try to begin again. That way, you'll have no excuse to try it the moment you remember.