Our present personalities are basically the combined habits of this lifetime (birth), built on the combined habits of previous lifetimes (births), all of which have left their mark (sometimes deep and sometimes not so deep) on our consciousness.
It may well be that habits such as becoming angry, upset, anxious, stressed, sorrowful or scared, have been with us for so long that, they feel a natural part of our inner world, so natural that when someone says our true nature is not anger but peace, not fear but love, not aggression but acceptance, not anxiety but calm, it does not feel right. And even if it did feel right for a moment, we have become so attached to our old habitual moods, emotions and behaviors that we do not really want to change. It may even be the case that we have become so weak that we need help to change. It seems much easier to stay the way we are.
As we begin to meditate and develop our spiritual practice, our views on the above subject will fluctuate. When that does happen, imagine you are having a conversation with yourself and teaching yourself. Give yourself permission to be peaceful by nature, full of love and joy by nature, naturally content by nature, wherever you are and in whatever you do. After a while, you won’t need to give yourself permission and you will find these states of being are there within you quite naturally at every moment. They are our original and eternal nature. Everything else is acquired or learned. In so many ways introduction to spirituality, like many other approaches to inner awakening, is as much about unlearning (the acquired beliefs) as it is about learning (new beliefs).