If you are paranoid about third-party trainers, remember that Fallout 3 ships with a built-in “trainer”: the developer console. Press the tilde key (above Tab) and type:
A game trainer is a separate executable program that runs alongside a game. Once activated (often via hotkeys like F1, F2, etc.), it modifies the game’s memory in real-time to grant the player advantages not normally available. These include: Fallout 3 V1.7.0.3 Trainer WORK