Your phone rings. You answer and hear your friend's voice. Without evening seeing the contact info, you know who it is. The sound of her words is instantly and unquestionably recognisable. Your partner asks from the kitchen who it is, and you reply. You know your partner's voice as well as your own, you tell yourself.
Let's pause right there. 'You tell yourself.' How do you tell yourself? Oh, yes. It's the voice in your head saying, 'I am as familiar with my partner's voice as well as I am with my own.' Just as you know your partner's voice, you recognise this internal one to be your own. In fact, if you are like most of us, you take this voice to be you.
Without stopping to consider it, we accept the inner voice as ourselves. Maybe we should stop and consider this. This is the voice that so often says things much less helpful than the example above:
If you had an actual person following you around all day pouring that negative stream into your ears, you would tell them to get lost! And if they didn't leave, you'd ignore them. But because we take the inner voice to be ourselves, we put up with it. We literally identify with it.
If you observe this voice carefully for any length of time, you'll realise that you have no more control over its utterances than you do over your friend's, your partner's or your mother's! These statements in your mind simply arise. You don't ask for them. Okay, you can sometimes wrestle them to your will for short periods, but before long, the voice takes off on its own again.
This voice is no more you than are the perceptions reaching you from the outside world. The inner voice is a stream of thoughts arising just as the sounds of others' voices, the smell of coffee or the sight of a traffic light turning red arises to your senses.
None of this is suggests that the thoughts are not real. You experience them. But they are not what you normally take them to be. You don't have to chase them away or keep them from arising in the first place. But you might want to treat them like you would a persistent, annoying person spouting often contradictory opinions.
Don't assume what this inner voice says is true. Don't believe the thoughts have any reliable tracking with the rest of the world or that they in any way compel or bind you.
You can't stop the inner voice from chattering, but you can recognise your freedom from it.