It takes at least 45 minutes and 30 minutes to start burning fat ~ Sit-ups can shape your body, but you can't lose weight ~ Besides jogging, you can also walk fast and do aerobics ~ I downloaded one from the Internet for 50 minutes every day, but it's relatively easy to stick to it ~ I also downloaded a light card from Mint, and com can monitor your daily calorie intake to lose weight ~ It's still effective ~ It's important to stick to it ~