Oh wow... you just described me with frightening accuracy. I’ve never seen my issue described so clearly and concisely. Basically, if there aren’t negative consequences for me not completing a task, my brain simply never gets motivated. It’s almost as if my brain is saying: “meh... you don’t really have to do this... so go play on Facebook some more”. If I could resolve this issue which has plagued me for years, it would revolutionize my life and career.
When in doubt always best to talk to a doc. Best case you are completely fine, but doesn't hurt checking. (The irony is that people with ADHD are probably the least likely to get up by themselves and make an appointment given that there are no consequences of not doing it lol)