There are two ways of losing weight. We can cut off some flesh. This is what we try to do when we feel like running away from a relationship not working out the way we want. But it would be painful and leave deep wounds, and we will perhaps keep blaming the surgeon for the damage.
Or we can lose some weight through intelligent dieting and exercise. We have to think whether the way we are leading our lives is good for us. Our associations, the thoughts we are exposed to, the sensual temptations that are there in our environment - are they adding to our mental unrest? If so, it is time for a little diet-control. Also for exercising those unused muscles of will.
In yoga we exercise a lot of those muscles that are usually neglected. "Willpower" and "Saying No" come into these categories (Saying "Yes" may also be an unused muscle for some!). Let us sometimes exercise those muscles - just for the sake of it. This is the practice of tapas.
As the minds comes to know itself more and more, rajasic energetic muscles build up and tamasic lazy fat reduces.
