It's a built-in design flaw of adapting. That's the intention when we design habits, adapt to circumstances and learn - that the new abilties become innate and can be used as second-nature. It becomes a problem as we add habit onto habit because we can pull ourselves in opposite directions. It causes people to get physically twisted up and age faster, stresses their systems.
The ways around it that I know don't necessarily involve "awareness" on the front end. They involve deliberately disassembling the habits. In fact, it seems to work best to not have a new habit in mind to replace what you are intentionally disassembling, but just remove what seems to be in the way that is outdated. It takes a willingness to experiment and to feel wierd.
If you use your observation/awareness with the intention to undo the habit BEFORE you have made any changes to actually stop the habit, you will only notice your habit, or nothing special because your sensitivity to the habits has disappeared. Turns out, rather than 'awareness' it's more of a timing challenge.
You can use the sensual world to give you feedback about what you are doing. Noticing when you are doing the old same thing will help you remember that you wanted to respond differently. I guess that's where the awareness comes in, remembering to notice. Most people only notice their objectives, their vanity, no consideration of their means, only their intention.
Say you know what your habits are, then you make a change deliberately away from them, THEN if you use your observation/awareness, you're more likely to notice something new at that point. Then you get the awareness insights.
You will usually sense differences in comparison to whatever you have been doing when you stop doing it and sometimes these differences will feel really paradoxical and positively strange. Descriptive ability is a skill factor in carrying through by not letting the habit resume control - it's usually when you can describe differences that you can know what is happening in fact.
Usually it takes practice to sustain existence without the old habits. I think of awareness being more of a sensory effect, and a sort of wisdom of how to intepret the results of your experimenting when you feel wierd and unfamiliar after making a significant change.