Yes, really. Even when you've understood how every choice you make is controlled by part of your brain over which you have no control... it's still not the easiest concept to grasp that everything you do tomorrow is already decided.
So to help with that, start with some things that you would have no trouble accepting are pre-determined.
Your alarm clock. Powered by a battery and a crystal of quartz, I'm quite confident that tomorrow morning my alarm will sound at 7 am. I've set the time and I've set the alarm and in doing so, the atoms inside that clock will continue behavining in an entirely. The action of atoms, once set in motion, will not change unless something causes them to change. In the case of the alarm clock, it's humans that have caused the atoms to behave in a particular way: the manufacturing humans harnessed the atoms inside the clock, condemning them to behave in a way that I expect my alarm clock atoms to behave.
So what's the difference with a human? It's still atoms.
Attack the problem from different angles:
1) How you make a decision
2) The atomic level
3) Compare your life with a computer playing a game of chess.
Think of it at the atomic level.
How is it possible to think of our lives and choices as 'just the automatic movement of automatic atoms'?
The growth of a crystal is automatic, no one would doubt.
'Life' is no different from the crystal - start with a single cell, with a nucleus of DNA. Grow outwards.
Remember the school chemistry lab.