The trainers you find on old CD-ROMs or forgotten forums from 2006 were designed for Windows XP and the original 1.0 executable of the game. They on:
Most antivirus software flags trainers as "False Positives" because they inject code into other programs. You may need to temporarily disable your shield.
Please note, creating and using trainers should be done ethically and within legal boundaries. Ensure you're not violating any terms of service or local laws.
Once the game is running, press the designated function keys (e.g., F3 for health, F4 for ammo) to enable the cheats. Alternative: Built-in Console Cheats