Concentration on the process of breathing is absolutely not the way to do mindfulness meditation.
I've been meditating for a while, and mindfulness is just one of many many methods.
Mindfulness meditation works what is called the "open aspect' of attention, where you are concentrating on yourself, not on something external - like say a picture of jesus or buddha, or even on the breath. It is designed be a mental workout so to speak, to improve this open concentration but also improves the ability to be less judgemental towards yourself bc it practices making a note of yourself without reflection, and this taking of note without reflection or judgement becomes a bit more of a standard mental process so that you can be more aware of your body. You can judge yourself later all you like but that ain't the way to do mindfulness meditation.
Mindfulness meditation is also one of the hardest kinds of meditation to do IMHO, bc the act of concentrating on yourself vs something else is more easily broken by a noise, or whatever.
Anyway, all you have to do is sit or lie down somewhere (I prefer to lie down) away from your bed, bc all you do on the bed is hump or sleep mostly, so the pattern might just make you want to sleep more than anything or be a bit lazy with your meditation.
Just lie down, and concentrate on:
1. The sensations of lying down
2. The sounds that you hear - I prefer a pretty quiet place but if there are a few sounds from neighbors or whatever then that is fine
3. Your thoughts - this is the best one to do imo
The sensations of lying down- When you do this just break your body down into sections, and start with, say, your arms and shoulders. You should feel a bit more or less pressure in different points, just try to to feel that and take note of it. Does your back feel better/worse while lying down? How much better?
Same as with taking note of the sensations, you need to take note of every sound, after you do this for a few minutes you should start to pay more attention to the various textures of the sounds, and take a note of the birds chirping, how the pitch rises and falls depending on what tehy are trying to "say" or whatever.
3,. Your thoughts-- In meditation we have this concept of the "monkey mind" where your thoughts just naturally erupt in your brain while you are trying to meditate, i.e. what the wife will be making for dinner, paying a bill, etc etc etc. Just take a note of every thought that you think, and when you say "Hey, I just thought about xyz". Well that's fine, and it's also the aspect of mindfulness meditation. So keep doing that.
To keep the noticeable affect, it takes time, just like anything else. 4X a week, 30 min per session should do you if you want to take the affect of the meditation with you throughout the week. But just doing it say once a week wont have a lasting effect.