I've tested out dozens of productivity hacks, but my favorite is incredibly simple. At the end of each day, I write down my three big tasks for the following on a sticky note.
I love the sticky note format because it's small enough to force me to focus and fleeting, preventing me from getting too wrapped up in the past or future. I love doing it at the end of the day as a way to mark my work day 'done,' so I can be more present in the rest of my life. And, I love being on autopilot first thing in the AM, tackling my most important issues.
Try it this week. Three things. One post-it.