I work a full workweek too, sometimes more than 40 hours a week, and the way that I've manage to exercise 6 days a week is to make it a part of my life.
In the same way that I wouldn't skip eating some kind of dinner, I don't skip exercise.
It is just part of my routine. Dinners with friends or movies or whatever take place AFTER my exercise. My BF knows that I am not skipping out on exercise for him (unless it's really urgent and necessary).
It becomes a part of your routine and then later, you'll find you miss it.
Will you lose weight without exercising? Yes, you will lose weight because it's about how much you eat and not how much your exercise. The amount you exercise off (in terms of calories) is really very little with how much control you have over what you eat.
But exercise is good to keep your muscle tone, to promote your bones, to take stress away, to raise those magical endorphins and to give your body a new shape.
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