Here is a wonderful exercise for letting go. In our culture, we view the cycle of the breath as beginning with an inhalation and ending with an exhalation. There are cultures in which they view it going the other way, beginning with an exhalation and ending with an inhalation. When I need to let go, I use this image of the breath. I first exhale, releasing whatever I am holding on to, creating space in my body, mind, and heart from something new. And then I inhale and bring in wonderful new energy to fill those spaces.
Use this idea in your breathing exercises or during Savasana. I find it particularly helpful when I am feeling stressed and in need of a deep surrender.