SimchaMinute by Rabbi Avigdor Miller
There is a peril in mere "prayer." One may fall into the error of making prayer an expression of his own will and personality, and he may conceive of G-d as a passive and inactive Being Whose attention is summoned at the whim of the individual.
Such a person does not really pray to G-d but to himself. His fervent prayer may be an ecstasy of self-adoration. This is then not prayer, but idolatry. — Rejoice, O Youth