Hi, I am 22 years old 5' 4" and weigh 190 lbs. I tried starting a 12 wk beginning runners' plan with a 3 mph walk pace and 6 mph run pace. Once I switched from walk2/run1 to walk1/run2, I struggled because of my heart rate and my calves throbbing. Next, I tried speed walking for 45 minutes a day, but I just don't feel like I'm working out. I want to do more. I am able to run for 30 minutes at a 12 minute mile pace (snail's pace), but I want to speed up AND lose weight. I have read varying opinions/advice, so I am confused as to what I should do. Should I stick to the walking plan, slow down the running pace for the walk/run plan, or just keep up the 12min/mile jog?