“Just do [X]” does not compute, whether X is “yoga”, “sports”, “[specific diet]”, “the laundry”, or simply “it”. It is never simply “just”. The inability to “just” start doing a thing (especially without any immediate reward) is one of the central symptoms of ADHD and if you say “just do [X]”, you’re essentially saying “just don’t have ADHD”.
ADHD also doesn’t mean you are/were bad in school. Not by a long shot.
Also why we endlessly do the hip wiggle to avoid going to the loo until it hurts.