Joyless living? Not at all! 

When you set out on the Paleo/Crossfit journey and join a community of like-minded individuals, the sense of belonging will bring you satisfaction. When you set out on a crusade to bring the "health benefits" of your new lifestyle to the ignorant masses, the sense of superiority will bring you satisfaction. When you smite the carb-lovers who stand in your way and claim their treasure, the bloodlust will bring you satisfaction.