Only a few months ago, I started looking at it. It turns out that sending a letter is a multi-step process. From printing something, signing it, writing the address (I hate my handwriting), going to the post office (often too loud, with long waiting times), sending it (with a proper type of email). All with delayed feedback (a killer for ADHD-like motivation). All in a way that a SINGLE mistake (e.g. sending 2 copies instead of 3, page 5 being unsigned, a missed deadline, etc).
Yes, therapy won't solve it. I am meeting weekly with a therapist for emotional stuff (but who is virtually clueless about sensory processing issues related to Autism/ADHD) and a "Psychologist on the Spectrum" (it's her FB page) purely for talking about such matters.
Ad substances, in my case, Modafinil works better than Methylphenidate. Modafinil makes me focused while reducing anxiety.
I struggle with it too and have not found a solution to it. There is a class of tasks which is really hard for me to get started on due to having failed at similar tasks in spectacular ways in the past.
The physician who ultimately prescribed the medication informs me:
1. Methylphenidate aka Ritalin is not addictive (and I had no problem stopping it for some years when it made sense)
2. Probably every adult could benefit from its use at specific crunch times. (But not permanently unless you're actually diagnosed with ADHD)
The FUD I've experienced when I mention Ritalin always surprises me.
I'd imagine it could first of all be difficult to diagnose because the symptoms might occlude each other (i.e., 'getting important stuff done' despite the ADHD, thanks to the panic of failing something, up to a point) and also a challenge to medicate both at the same time, since I'd expect anything 'raising vigilance' to also cause anxiety and vice versa.
The doctor and psychologist I worked with prescribed a small dose of medication that affects multiple neurotransmitters. In addition I've found some mindfulness exercises and aerobic exercise helpful.
20mg instant release Methylphenidate makes an incredible difference. I can actually prioritize things properly and take care of family, housework, my body, and long term goals and all that before bedtime!
It used to be night after night doing the housework dead last at 2am or not doing it at all and experiencing marital strain.
Pretty life changing.
In no way I want to advertise mph as a silver bullet for such problems, but at least for some people it works like a charm.
That said...let me start with my premises. (1) I don't think risks are very high/unknown, and this point (2) but let's face it... an adhd regimen is an "uppers" regimen. So... my bias is moderacy. At the least, it encourages you to be specific in your aims. Are you trying to be more productive 9-5, minimize pathological behaviours, or are taking uppers to handle that 9th or 12th hour of work.
I'm diagnosed and experience exactly what you describe, but there is also a decade of severe underemployment, risky impulse behaviour, big financial hits, marital strain and a litany of health problems.
The harm can be pretty subtle despite being obvious in retrospect.