A BP of 100/60 is normal for your age.If you are concerned that it might be too low a standing BP would help. Normally on standing the systolic BP will decrease by 5-10 mm Hg and the diastolic BP will increase by 5-10 mm Hg. If you get lightheaded or dizzy on standing or your systolic BP decreases by 20 mm Hg or more OR your diastolic BP decreases by 10 mm Hg or more your blood pressure is too low