Great to hear you're enjoying Headspace and finding it so useful.
At the very heart of meditation is this idea of loosening the grip we have on our sense of self. At first, this might sound a little scary, or even abstract, but broken down it starts to make a lot of sense.
Imagine experiencing a thought which says "I'm no good," and believing it, taking it as something real and substantial and spending a good bit of time and effort in thinking and feeling rotten about it. Now imagine experiencing that same thought, knowing it is simply a passing thought, in no way identifying with it or using it to reinforce a storyline in the mind, and instead, letting it go. This is the potential of meditation.
So, when we experience anxiety, rather than getting lost in it and thinking “I feel anxious,” we witness the anxiety and say "oh look, anxiety,” before letting it go. Likewise, when we experience a thought which is unpleasant, or hurtful, or somewhat critical towards ourself, rather than grasping it and using it to create a new storyline, we simply see it clearly for what it is and let it go. So it is the difference between experiencing something and becoming something, witnessing anxiety and being overwhelmed by anxiety.
Over time, applying this same approach to all parts of life and to all passing phenomena can have a very profound impact on our perspective and experience of life. Of course, we still need to engage the thinking mind, and as human beings, we still experience all types of emotions, but we are no longer controlled by them, swept away by them; instead, we are free. This is what it means to step back and let go.
Somewhat ironically, low self-esteem or low self-worth is actually a result of over-identification. So we may well think that it is because we do not think enough about the self, but it is actually because we give it so much importance, approaching it in a critical way. So, rather than thinking we are the best in the world and brilliant, we instead think we are the worst in the world and not very good. The focus on the self is still the same, it is simply orientated the other way.
So, along with letting go of all the storylines, we also need to make sure we let go of the critical and judgmental aspect of mind. Can we start to treat our own mind as if it was the mind of someone we love? Can we start to be more forgiving toward it, more gentle, more kind? Again, these things take practice, but with time they become natural and we do not even need to think about it. Needless to say, it is well worth the effort.
Warm wishes, Andy