Because wanting to do something and starting it run on different systems. In ADHD, the starting system doesn't switch on just because you want it to — it switches on for interest, novelty, urgency or challenge.
Wanting and starting are different jobs
You can know exactly what to do, care about it, and still sit frozen in front of it. That gap is the heart of task-initiation trouble in ADHD.
Wanting is a thought. Starting needs the brain to release the energy to act — and an ADHD brain releases it on its own terms, not on command.
What switches it on
The ADHD brain tends to start on four things: interest, novelty, urgency and challenge. That's why a deadline tonight gets you moving when a deadline next month doesn't, and why a new method works brilliantly for a week.
You can borrow these on purpose: make the task a little more interesting, a little newer, a little more urgent, a little more of a challenge.
Shrink the first step
A big task gives the brain nothing to grab. Shrink the first step until it takes under five minutes and has a finish you can see: "open the file and write the title", not "work on the report".
When a step is that small, starting stops being a big decision.
When you're already frozen
If you've been stuck for a while, don't argue with yourself about why. Change one thing in front of you: stand up, move to another room, or say the first step out loud.
Then do only that first step. Not the task — just the step. Stopping after it is fine. Often you won't want to.
Use something outside your head
Don't rely on willpower to fire the start. Use an outside cue: a timer you can see, or a person. In Zalfol, Sponsoring lets you choose someone who witnesses your progress (it isn't Zalfol Care — it's a person you pick).
And whatever you've been told: this is not laziness. Lazy is not wanting to. This is wanting to, and being stuck anyway.