Odds of Hanging On
Stay physically fit and perform well in both training sessions and on calls and you should be fine. Accidentally set fire to your own fire station, and your job situation may be slightly more tenuous.
Honestly, your biggest concern isn't about being relieved of employment. It's about suffering the debilitating or fatal effects of one of the infernos you're forced to face. If you lose a limb or have third-degree burns over thirty percent of your body, yeah, you might lose your job, but unemployment might also not be the foremost thing on your mind.
Work on hanging on mentally, emotionally, and physically; if you can handle that trio, your job should still be there for you.