This one's not for the faint of heart. Take your 30 minutes of physical activity for the day and try to accomplish it all in one shot. By walking or running nonstop for 30 minutes, you'll elevate your heart rate and blood pressure, activate those sweat glands, and breathe in plenty of air and oxygen. When you walk continuously for 30 minutes (or more), your body will burn through the stored sugar calories in your system and begin to burn fat. This can be tough in the beginning, so be sure to check with your doctor before giving it a try.
Step it up:
Instead of trying to walk or run more quickly, choose more hilly areas. You won't get as far, but you'll get a far more vigorous workout.