42. Short brisk walks of 10 minutes, or longer 40 minute walk.
http://walking.about.com/od/hearthealth/a/...rtension906.htm

According to a study in the September 2006 issue of the Journal of Hypertension, taking short, brisk 10-minute walks four times a day can decrease your blood pressure for 11 hours. Taking a 40-minute continuous walk can keep it down for seven hours.

This is close to my number #3 of having a 30 minute walk a day. But this is the first one I've seen that a walk as short as 10 minutes has an impact.