A mantra practitioner should have a clear understanding of how mantra practice works and what to expect, and what not to expect. Actually mantra practice should never have expectation, but instead faith.  The right attitude is to do the practice of the mantra with faith and with all the possible devotion, and not expect any outcome. The outcome is up to Existence (or God) —not up to us. That is why the first thing that a mantrin should understand is that the right attitude is that of trust and patience, or as Jesus said, the "thy will be done" attitude.