In the scheme of nature, there is a free will for an individual to do something or not to do something or do differently. This is the free space available to us.
Destiny , on the other hand, plays its trick starting with the birth of a child. Why one is born poor and another rich ? Why one is healthy and another has serious birth defects? One loses the mother the moment it is born? One is born dead? The questions are too many.
But what is the force which causes such disparities ? Whether God is to be blamed for this partiality?
The only logical answer could be the Karma Theory which explains that the human being takes birth to exhaust his Prarabdha Karma. This gets extinguished only by experiencing in the world , going through the vicious cycles of pleasures and pains. In the process there is always a little scope to do some action within a limited domain. Just like a Cow which is tied by a long rope has the freedom to move within the space determined based on the length of the rope, human beings have some free will to exercise. Beyond that limited area the tied cow cannot roam about. This represents the force of destiny. The reason why people lose their precious life suddenly due to accidents, dieseases, natural calamities like Tsunami , earthquake and so on cannot be otherwise explained.
Self- effort is absolutely essential for any one without taking shelter under the guise of destiny. Therefore one has to do his Svadharma in a given environment without any expectation. If destiny decides otherwise, one should have the will power to take it in his stride in a positive manner. For this meditation techniques help a lot to make one develop equanimity towards the dualities. One should take caution not to abuse the little free will that is available to him.