Check out THIS ARTICLE from the European Heart Journal, the findings of which suggest reduced health risks may be attainable through relatively modest amounts of vigorous physical activity accrued in short bouts across the week.
Vigorous activity for 15–20 min/week were associated with a 16–40% lower mortality and further decreases were observed with up to 50–57 min/week.
As always, I am not a physician and this is not medical advice. You should always consult with your healthcare provider prior to starting or changing an exercise program or physical activity.