The Source of Suffering and Letting Go

All your suffering, in fact, has only one reason. You are clinging to something that does not belong to you. Master Hongyi once said: Everything you try to control is actually controlling you. You think you are trying hard to grasp it, but in fact, you are being dragged by it. You think pain comes from loss, but it is actually because you are unwilling to let go. What is the hardest thing for you to let go of right now?