In addition to writing a regular to-do list, it's also important to recognise everything you actually did get done in a day — even if wasn't on your initial list. Life happens, and there may be a task you unexpectedly have to give your attention to, resulting in one or more unchecked boxes for the day. Our brains love ticking off completed tasks, so when this doesn't happen, it can leave us feeling unaccomplished and down on ourselves.
In fact, according to the Zeigarnik effect, we remember the things we still need to do much better than the things we've already done. So, even though you were productive in the task that came up unexpectedly, your brain will likely forget you even accomplished it, while also inducing guilt for not completing something else that was on the list. To combat this, come back to your list and write a new "done" or "completed" list with everything that you completed that day. It can even be as simple as brushing your teeth — the more boxes you get to check, the better!