I will make this thing clear for everyone that we are responsible for our good and bad deeds because it is we who do good and bad things and God has nothing to do with this. Secondly, everything is not pre-destined.
There are just few things which are predestined your birth, your death is predestined, whether you will be a famous person or not is predestined. Whom you will meet in this life is predestined, from whom you will get separated is predestined. But whether you will be wake up in the morning and do your Yoga or not, is not predestined, it is you who decides that. Whether you Respect your parents n try to make people happy around, is not predestined. It is you who decides that. Whether you will accept the bribe, speak a lie, commit a theft etc. is not predestined, it is you who decide.
Similarly if you want to be compassionate and give away things in charity then it is not predestined, it is you who decide. Nature has given you the brain and intellect to make your decision, nature doesn’t interfere in that and you are responsible for making your decisions. So you are responsible for your good and bad deeds. Thus you are responsible for all the fruits which are coming to you good or bad.
Ok, what does destiny do? Not much, actually even destiny is sum up and boom up off your accumulated Karmas. What is destiny? Destiny is all the sum total of your past good and bad karmas. So no one has written your destiny, you have written your own destiny.
As such few things are beyond human control like your death, you can’t evade it. But, you can definitely prolong your life, this is in your hand. You can prolong your life by following the right system in your life. The importance of Karma is always going to be there no one can minimize it. We have to accept this fact that we are responsible for our life.