When you are mindfully noting, you have thoughts in your head and this is one of the benefits of the mental noting technique. You are actually putting a thought in your head, it is a neutral thought, it describes what is happening, nothing unbeneficial about it. Think of it this way, you have a box of apples and you have to give a complete box of apples to a friend. But when you look in the box you find out some are rotten. You don't want to give your friend rotten apples, so you take some out. But now you have holes in the box. You have to go and get fresh ones to put in. By putting in the fresh ones and taking out the rotten ones, we keep the box nice, and we give good apples to our friends.
By using mental noting before the "rotten" thoughts get in, we actually fill the box before other rotten apples, so to speak, get in there. It is as if we are making sure the box is good apples from the beginning. So the mental noting works in this way a bit, in that it actually stops other thoughts getting in.
Now every time you get distracted, it can be traced back to a thought. Try to trace it back, what happened? Maybe you are angry with your brother, you are sitting there angry with your brother, sister, mother, father, doesn't matter. Anyone. And all of a sudden you realize, "Why, why am I upset with them?" And you think back, "Oh, the dog. It was their dog, always chewing my table, bla, bla, bla". "Okay, why was I thinking about a dog?" You trace it back a little more, "Oh, I heard Joni bark. I heard Joni bark and I thought about dogs. But what was I doing before I heard Joni bark?" And all of a sudden you can't remember what you were doing before that. And that is because you had dropped your mental noting for a while, the barking distracted your attention and so you went off and eventually started thinking angry thoughts about your brother, sister, whatever.
Now if the mental noting was going on before Joni barks, and then when Joni barks, you note "hearing, hearing" and you go back to the awareness of the breathing. So if your mental noting is going strongly, it is going to catch Joni barking only as "hearing, hearing" and go back to the breathing. If your mental noting is not going, then it is very easy to go into barking. "Dogs, oh I hate dogs, my cousin has one and bla, bla, bla". This is where the mental noting is a major tool for preventing the arising of unbeneficial thoughts in your mind.
A lot of people have resistance to mental noting and feel, "Oh, I don't want to do it." But keep in mind that if you get lost a lot, then you need to get your mental noting up stronger than before.