I was doing a bit of journaling at the end of what felt like a long day, noting the list of things that I had completed from my task list. It was a very short list of completed items and I commented in my journal that the list was terrible, that I could've done much better. Then I wrote, there's always tomorrow.
But no, there isn't always tomorrow.
You don't know if tomorrow will come, but that doesn't mean that you should live in fear of tomorrow not coming, or that you should live with the assumption that it's not coming.
Instead, it means that you do your best today. You put in an effort to do the best, to make the day as productive as possible, to live it in such a way that you feel it was a full, complete, and good day, and that if you didn't have tomorrow you would feel content in the realization that you treated today in such a way that it proved you were grateful that you had it.
So when you find yourself saying or thinking, well, there's always tomorrow or there's always another day, realize that there may not be. And that's okay.