I don't believe in Karma, neither do I believe that your destiny is fixed in such a way that nothing can be done about it.
Yet on one hand, the Bible does say that the number of days in a person's life is fixed, even death by suicide, murder, an illness or accident is foreknown by God. So is the case of a dramatic rescue from danger, a recovery from illness, a failed suicide attempt followed by a change of mind; also as is the case of level of education one would receive, what kind of vocation he would pursue, whether successful at his job, or a drifter, whether he'll end up rich or a beggar, whether he'll be straight, gay, bi, married with children, remains single, whether he chooses good or evil.
All these things God knows about a person even before he is conceived in his mother's womb. And God ordains who his parents will be, where and when he will be born, and how many days he will live, whether he dies at birth (stillborn) or lives up to 36,525 days (a hundred years).
And yet we are given a choice whether to believe in God, or not to believe, to submit or to rebel, to believe in Creation or to believe in evolution, to convert to Christianity, to Judaism, to Islam, Buddhism or Atheism, or remain agnostic.
We decide where to live, our vocation, we choose whether to marry, to stay single, to have sex with a guy, or refrain. We decide to get a passport and travel, or stay at home. If we fall ill, it's up to us to seek treatment, and if one are depressed, one choose suicide, or make an appointment to see a counsellor.
Two contradicting issues? Yes! But both are equally true.
That is the mystery of the Universe.