Sometimes you may feel that you have amazing, tremendous meditation, and at other times you may feel that you have no meditation at all. This characterizes meditation experience, which fluctuates a great deal. Realization, which is distinct from experience, does not change, but experiences can fluctuate a great deal or alternate between good and bad. There will still be times when you will have what you regard as good experiences and, in contrast, what you regard as bad experiences. When that occurs, just keep on looking. Don't get distracted or sidetracked by the experience. Whatever meditation experience arises, you should recognize that it is transitory. As is said, "meditation experience is like mist, it will surely vanish."
Experiences are different from the actual fact of the recognition itself. Because they are ephemeral experiences, they aren't worth investing in. So if you have a bad meditation experience, do not be alarmed, because it too will vanish. If you have a good meditation experience, you need to continue; if you have a bad meditation experience, you need to continue. In either case, you simply need to continue to rest in this recognition of the mind's nature.
--from Pointing Out the Dharmakaya by Khenchen Thrangu Rinpoche, foreword by the Dalai Lama
