Question

A rest day from what? Cardio? Weights? How intense are your workouts? A bit of exercise 7 days a week isn't a bad thing but you do need to give your body time to recuperate. So vary the intensity, at the very least. As for weight training, your body does need rest after each workout so maybe rotate between upper body one day and lower body the next if you really want to go 7 days a week.