6. You trust calorie-burn estimates.
Oh, how sweet it would be if 20 minutes on a cardio machine really did blast 400 calories. But like most things in life that sound too good to be true, those digital displays broadcasting mega calorie burn are often bogus. Research presented at the National Strength and Conditioning Conference found that elliptical trainers overestimate calorie burn by an average of 30%. But you can still utilize those calorie counters as a gauge of how much you’ve exercised—and as a benchmark for ramping up your workouts. Try to raise the number you see on your machine every week, and you’ll continue to make exercise gains.