It depends on what shape you are currently in and if you have been running. You might start off with walking 20 munutes a day for a week, then adding in some running. You can build up to 30 minutes a day. If you really want results, combine the treadmill with strength training. For example, do Jillian michaels "the shred" every other day and the treadmill whenever you can. Cardio helps you burn fat and the other to lose inches and firm up. The most important thing is your diet though. . EAt lot's of lean protein, fruits and veggies. Watch out for too many procesed type foods (lots of sodium). Just take the steps you need to lose weight and try not to get so stressed.