There is some good advice in this thread, but if you do have ADHD, then the advice is only as good as your ability to carry it out, and saying “just do the thing” will only end up demoralising you.
From my perspective (42, diagnosed with ADHD four years ago), it’s been damn near impossible for me to noticeably improve myself. It’s only when I reflect on my progress that I begin to notice positive changes.
Ultimately, it’s about training your perspective on a task. Are you failing to do things, or are you choosing to prioritise other tasks instead. Do those other tasks have positive outcomes (however tenuous they may be)? If this is the case, then you could work on choosing to prioritise the tasks that are expected of you.
In terms of my working day, my job is an issue for me, as it doesn’t really have a set form, and is almost entirely self-led. If I don’t do what’s expected of me, no one really notices, and that’s actually a problem for me, because left to my own devices I’ll gladly spend all day fucking about online, then feel like shit because I’ve not been productive*. So I’ve learned to tackle this by physically writing myself a To Do list first thing in the morning, that I then input into a daily timetable spreadsheet. Then I use an app called Cold Turkey to block access to websites of my choosing for a period of time. Only then am I able to focus on the tasks at hand.
In time, your brain will (hopefully) begin to mould itself around a different way of being, and while it will not likely become second nature to you, it will become easier to recognise when your distraction has taken control.
*of course, almost all of the problems we face are as a result of being forced to exist in a capitalist society, where we’re all trained to assign our personal worth to the worth of the work we produce. If we neurodivergents were able to live outside that paradigm, we’d be fine.