High Blood Pressure Help!?

I am a 21 year old female that is not overweight (5'6'' 130lb), and who exercises regularly (4-5 days a week). However, my blood pressure is about 140/90. My doctor says it is even higher for me because I am so young. He told me to measure my sodium intake on an average day. After a week of monitoring it, (not eating any differently) I found I rarely go above 2,000 mg a day (you should not go above 2,300-2,400) Is my case strictly hereditary, since I practically do everything possible to not have high blood pressure? Should I inquire about prescription drugs to control this? What else can I do about it? Will it just keep raising with age? I am especially concerned since my father died of a heart attack at the age or 41.