I don't know enough about the science of what you reply to, but neurodivergence is not a mental illness, so not sure what you're implying here. I'd also wager people leave rooms by the door because it is easier, so I don't think that requires a habit or conditioning.

Conditioning does not equal "habit". You can train a lot of things to the level of muscle memory (like I always check seat belts before moving and avoid taking them off, or how I mentally recall coordinated turns even when turning while walking), but it's a completely different set of behaviours - or at least totally different difficulty level - when it comes to "habits" that take longer time and aren't linked to directly executed skills - think like making a habit of training every few days to get more fit, or even habit of checking email at the start of work day.

People with ADHD don't experience the task-completion-reward-loop like others; i.e., it's vastly diminished. This makes building habits more difficult because it looks more like a task that takes energy rather than continuing an establishes behavior.

> When you leave a building, do you exit through the door or the window? I assume the door.

This is a poor example; I think discussing workouts suffices. If a workout is mentally engaging (bouldering, arial silks, an active team sport) it's easier to engage in than a simple, unengaging, repeated task (weight lifting, running, cycling). Why? Because the mentally engaging exercise is appealing because it absorbs attention, which can help overcome the diminished reinforcement cycle.

If you don't already have a workout habit, framed to an ADHD person, it's a crap value proposition: spend time and energy to do something boring and you should feel better, but historically the things people say will make you feel better never have that effect, and you only ever end up with less time and energy to do the things you actually want to do.

In my personal experience, I loathe going to the gym on my own because it's boring and takes time and energy that I would rather spend interacting with friends or playing games: it's a "task" that I "should" do, but it never feels rewarding when I do it. However, if I go bouldering, I'm not bored because my brain focuses on the "problem" of positioning and coordination and I feel like I"m having fun because of the problem I can satisfy my brain with, which distracts me from the energy expenditure both in the logistics (going to gym, changing, showering, etc) and from the actual work my body is doing.

Except it’s harder and harder the more you age. And it’s true for animals too.