I don't know about you, but I have a dozen different responsibilities in my personal and work life combined. Multiple projects in the office, constant KTLO time spent on administrative jobs at home. This leads to a packed schedule, where being productive suddenly becomes a requirement and even an addiction. I follow zero-inbox strategy, which works quite fine; as of writing this post I have only 3 emails in my inbox.
Prioritizing tasks in a packed schedule is a different kind of story, but what I will focus on is staying on top of every task in the backlog. Greater the number of tasks you have, amount of information you need to absorb increases dramatically. Suddenly, you have to keep an eye on a client communication that happened 2 weeks ago, while also focusing on testing & deployment of a new feature and you receive a meeting invitation on a new product you are working on. This can easily become the definition of chaos.
If I were to name the most significant accomplice of chaos, I would say it's my memory.
Don't Trust Your Memory
That was my biggest error so far. I trusted my memory and had the wrong bias where I believed I was good at remembering certain details about an event. That is true, but only if that event was something out-of ordinary, something unexpected, irregular. Remembering details for this kind of events in life is how our brain works though, so it's no surprise (I'm no special, most probably neither you are).
As a result, I make daily and weekly plans on Sunday evenings or early Monday mornings. I record them in my notebook - I best work by actually scribbling notes on a real paper, hence no digital notes. This though doesn't apply to certain work-related stuff, primarily when coding. It's the only exception, obviously. Nevertheless, if someone asks me some question about any project or initiative, I usually have the answer in my notebook.
Key point: whenever you have an idea, a to-do item during a meeting or some action item you need to work on, record it as soon as possible. Then at the end of the day, organize those notes into your actual plan.
Do not think to yourself, I'll get it done when I go back to my desk. That will almost never happen, unless you have a rather comfortable work life.
Only downside to recording everything in a notebook is you do write a lot. That's, however, another motivation to complete as much tasks as possible, because you don't want to re-write them for every other week!