Because the mind can't be in two places at once, developing the skill of moving our minds into the present, into pure awareness, gives us the skill to let go of our thoughts. The best part is, the letting go part happens automatically. We don't have to work at letting go. What we do work towards is training our minds in the act of moving from thought into the present, into awareness, into direct experience. Our mistake is thinking we have to learn how to not worry, or how to not be impatient, or how to not get angry. But how can you practice not doing something? Impossible! What we can and do need to practice is that mental movement, the practice of moving our minds gently, kindly, from thought to awareness. There is no worry in pure awareness, no impatience, no anger. Those are thoughts attached to the past or the future. We can feel the physiological responses to our thoughts of anger and impatience and worry in awareness, in the present. Our hearts beating fast, our blood pressure rising, our bellies clenching. One way of understanding this is to think about those feelings in the body being the by-products of our thoughts of impatience, worry, anger, etc - they aren't the anger itself - and once we let go of the thoughts, there is no more cause for these feelings. By letting go of the cause of our anger, we have let go of anger.