The "practice" of contemplative prayer can be an obstacle to prayer--if, consciously or not, we come to it and execute it wrong-headedly as one more project, one more task. Dismiss thoughts! Form intention! Desire God!
No! This is not a job or another task! "You have only to keep still." (Exodus 14:14) Let go of thoughts not as a project in itself, which only reinforces religion as agonistic self-involvement, but to sit still and hear God calling within. It is not a strenuous reaching up to God, but the practice of noticing that he delights to descend and live within you.