It just doesn't happen. You need to make the decision every day. Even if it has become a routine you can't forget it still needs that little nudge to get started.
It's easier some days, harder the other. But it doesn't matter. You just do it and that's it.
It's not for all. It might feel intimidating, forced. You might even feel it controls you instead of you being in control. But it doesn't. I can quit any day I want. But I don't want to. Not today, not in any foreseeable day in the future.