If I ask you to pay attention to any tension in your shoulders, something interesting usually happens.
They will spontaneously drop, with little intent on your part.
What happened? You paid attention and the holding broke into awareness. You realised you were actively maintaining it. The truth became apparent.
Becoming aware of a contraction is all that is needed to release it.
Adi-Da often talked about the self-contraction in this way. He would often use his fist to illustrate the contraction in action.