Well, yeah: the lack of motivation is the problem. But here's the thing: just like a depressed person can't just "snap out of it", someone with ADHD cannot just make themselves get the motivation. Why? Because we can't remember that we need to. ADHD is primarily a working memory impairment.

All brains have an autopilot mode, and an ADHD brain on autopilot thinks thousands of thoughts at once. When I am not medicated I can be cooking, having an imaginary conversation about politics, planning the weekend, and listening to a song playing in my head - all at the same time, and doing all of the above badly. When I am medicated I do the same thing, but after 10 or so minutes a thought pops into my head: hey, you are distracted, focus! Without meds this thought may take an hour or two to arrive.

A deadline seems to raise the baseline of executive brain activity for a similar effect to the medication, but it's not guaranteed. Now try explaining to a boss who doesn't believe that ADHD is a thing why your performance is inconsistent. Don't you care about deadlines? I do, but I can forget that a deadline is a thing that exists in this universe.

OK, you'll say, just build routines. Discipline. Of course - I couldn't survive without routines. The trouble is: I forget I have a routine when my brain is in that fuzzy state. I can get to work, not know what my tasks are for the day, and start daydreaming. Why not just look at JIRA? Because in that state I don't remember that such as thing as JIRA exists in this universe. I actually have an alarm in my phone that tells me to check JIRA around the time I get to the office. I rarely forget, but when I do - the failure is epic.