A PMHNP is treating a 45-year-old man with bipolar I disorder who has been stable on lithium for two years. At a routine follow-up, the patient states, "I've been thinking about stopping lithium. I feel great and I'm not sure I even need it anymore, but I also remember how bad things got last time I stopped." His lithium level is therapeutic and labs are within normal limits. The PMHNP recognizes the patient is expressing ambivalence about continuing treatment. Which of the following responses best demonstrates motivational interviewing techniques to support treatment adherence?