This is an intended goal for the Bodybuilder career and will show up regardless of packs due to the way Objectives in the game work. After a conversation with some other modders (frankk, TwelfthDoctor1, and ChippedSim), we may have deduced a way for the game to allow you to skip this if you don't have the pack installed, but it will take me some time to code and test it. For now, I recommend using a mod like UI Cheats or MCCC to skip that specific objective, or uninstall the file for the Athlete career if you don't want to deal with it.