Why are we sometimes forced to behave in a manner which is contrary to our nature? It may seem that external circumstances propel us. The truth is we imagine our life a certain way and when things don’t pan out how we envisaged, we feel sad, frustrated or depressed. Out restless mind then prods us to act so we may get what we want. Note two important words here, “imagine” and “want”. Imagination is nothing but pursuit of a train of thought. When we contemplate on a thought, we are basically imagining. And when the same thought stays, it becomes a desire or an emotion. For, a want is a desire which again is a lingering thought. Why are some people more prone to negative or lusty thoughts than others, for instance? It mostly boils down to our tendencies of the mind. Patanjali gives the most beautiful definition of tendency in his Yoga Sutra :
Psychic imprints, resulting from karma, accumulated over many lives condition the mind and cause one grief.
The word karma here is meant to signify action and not destiny. Imagine a spinning wheel painted with bright spectral hues. Since it is spinning its face appears illusory white. In reality, there is no white colour on the wheel. It’s the momentum, speed at which its spinning that’s creating the illusion of white when the reality is far more vivid and colourful. Similarly, mind is always moving. Like the spinning wheel, it creates an illusion of reality of the material world. It makes the world look like a permanent place. However, that is not so.
Reference : A Million Thoughts. Om Swami.