How can we understand the fact that Reform Christianity holds predestination to be true yet not in a way that encourages fatalism?

As stated for instance [here](https://christianpure.com/learn/protestant-christian-vs-reformed-christian/) and many other places, Reform Christianity has as one of its central precepts predestination, i.e. Gd has already chosen some of us for salvation and some for damnation. Logically, this would lead me to be a fatalist: nothing I can do will change my fate. How does Reform Christianity so vehemently argue against fatalism at the same time? This is not a smug rebuttal (which would be naive) but rather a genuine request for the details. The way I see it, this is all a side effect of the I suppose well meaning starting point of the sovereignty of Gd, logically leading to predestination - from here, there is either some nebulous cop-out or indeed an elaborate reconciliation of this and avoiding fatalism which I would find great intellectual satisfaction in learning.