Consider taking as long of a vacation / sabbatical as you are able to simulate what leaving might be like and using that time to see how well you are able to st

Consider taking as long of a vacation / sabbatical as you are able to simulate what leaving might be like and using that time to see how well you are able to stick to a schedule / routine, be internally motivated, etc. It of course won't be quite the same as if you actually leave, e.g. you may be less motivated than if you actually quit since you know you still have the job to come back to, but should still provide some useful info re: your concerns.