Try running in 5 min intervals.{I started 2 min run 3 min walk} I am now doing 4.5 min run .5 min walk. I am not a runner type at all {6‘6" 280 lbs}. I also started a circit traing program with dumbbells this also helped with my cardio and strenth. This really worked for me in 6 months I lost 45 lbs, motivation to become a solider really helped to. I hope this helps.