If you decide your fate is in your own hands, it is. If you decide you are pushed around by circumstances beyond your control, you are.
The truth is, our fate is in our own hands to some degree, and also there are a lot of things that influence us and are out of our control or have been preordained (like where we were born).
But if you decide your fate is in your hands, your fate becomes more in your hands, and as time goes on, it becomes more and more true, like a small wave catching more of the wind and becoming an ever larger wave.
It is only a matter of where you put your attention. For example, if you pay attention to the forces that influence you beyond your control, you'll feel helpless, at least a little. Depression, or some degree of it, follows like thunder after the flash. When people feel helpless, they don't take actions they could take that would make their situation better. A belief in one's helplessness actually makes one more helpless.
Put your attention on what you can effect, however, and your life will go more the way you want it to. You're concentrating your attention where it counts. This makes you more likely to take action, and makes your actions more effective. Optimism follows. And as numerous studies have shown, including the thorough work of Martin Seligman, PhD, Kogod Professor and Director of Clinical Training in Psychology at the University of Pennsylvania in Philadelphia, the side-effects of optimism are better health, more success, higher self-esteem, and a greater feeling of control. You'll have a greater feeling of control because you actually have more control. Your decision that your fate is in your own hands has given you more control of your life.
Your fate is, to a considerable degree, what you make it.