I need to lose like 15 - 20 pounds. I was thinking of taking up jogging to aid me in doing so. If I eat healthy and do a slow jog (10 min mile) for 2 - 3 miles daily will this be enough? Is it better to say do 12 min miles for 3 - 4 miles? Whats the best way to speed up so I can eventually do say 3 - 4 7 min miles? Thakns.