Could spend hours talking about ADHD which in this case is about how it creates executive dysfunction. A better term would be to call it Intention Deficit Disorder.

From personal experience, I know what I should do and the benefits of doing it, but I can't seem to actually 'motivate' myself to do it. I think in this day of smart phones and other distractions, it's so much easier to say 'this other thing I rather do' and it's not a matter of 'will power' it's the brains dopamine system literally telling you that.

Of course existential thoughts of 'why bother now' would also lead to procrastination and demotivation to the point of only doing things last minute, which actually might be too late.

My opinion, find the root causes of why and see if you can personally resolve them, if not talk to a Dr.