DEAR DOCTOR K: You often recommend exercising for 30 minutes a day, most days of the week. That target intimidates me. Is it worth it for me to exercise less, say 15 minutes, three days a week? Or is there no benefit unless I commit to the full 150 minutes per week?
DEAR READER: I'm glad you asked that question, because there are a lot of people who are daunted by the thought of exercising that much -- and therefore don't do it at all. It is true that I do advise 150 minutes of moderate-intensity activity each week. But two recent studies, while not changing my view that 150 minutes is best, show that less than this still brings benefits.