Funny thing is that this is the ONE ADHD thing I don't have. My trick: Super-panic about being late.
The broader strategy is that I set an exact time that triggers the "panic mode". So for example when I need to take a 3 day trip, I put my open suitcase in the middle of the room and fill it only casually as is convenient, starting days before. Hours before departure, I'm putting what is still missing in, but very relaxed, and do other things such as shower, eat, whatever needs to be done. But like 20 minutes before departure, the "panic mode" is triggered. Whatever is still missing then is done with maximum stress, only absolute show-stoppers, no optionals, complete panic the whole time.
Knowing that panic mode is still there to help last minute, allows me to do the entire thing very relaxed.
Absolutely, I mean, we should still do our personal best when it comes to important tasks, but some days, our best feels like very little to nothing.
I already try to work with lists and break down tasks into smaller tasks, but that can lead to 30 items per week. If it's going really great, I do 25. But among the 5 failed tasks could be something really important, like a last deadline for a bill before it goes to court, tax filing before thousands are lost, even watering a flower etc. To others, it may appear like I achieved nothing, but honestly I'm already happy it went that way and some stuff got done.