It is the impact of the Guru’s grace that causes this very intense and rapid unraveling of karma. This creates tremendous pressure within your system, and the pressure exerts itself on your psyche, your personality, your emotions, your physical body, your health. It’s important to remember that this pressure is a good thing. This is where the rubber meets the road in spiritual life.
People can do spiritual practice for lifetimes with great effort and intensity, but without the grace of the Guru they’ll certainly get some experience and learn things, but the unraveling of the karma will not have been triggered. Up until this happens, all spiritual practice is aimed at gaining the Guru’s grace. And having gained the Guru’s grace, spiritual practice then becomes aimed at withstanding the Guru’s grace