A 48-year-old woman with no significant past medical history has an office blood pressure of 152/92 mm Hg at today's visit. Previous readings over the past 6 months have ranged from 145/88 to 150/94 mm Hg, all measured with a manual sphygmomanometer. She is asymptomatic and has no end-organ damage. According to Hypertension Canada, what is the most appropriate next step before definitively diagnosing hypertension?