A method of monitoring a human relaxation level and a user-operated heart rate monitor are provided. The user-operated heart rate monitor comprises a timing instant determining means for determining a plurality of heart beat timing instants from a user's electrocardiogram; a relaxation calculating means for calculating an instantaneous relaxation measure value by using the plurality of heart beat timing instants; a relaxation reference calculating means for generating a relaxation measure reference value by using a plurality of instantaneous relaxation measure values, each calculated over a different observation period; and a displaying means configured to display a reference pointer indicating graphically the relaxation measure reference value and further configured to display a relaxation pointer indicating graphically the instantaneous relaxation measure value relative to the reference pointer.