Diet
Cardio
Stretching
Weight Training/Calisthenics
You need ALL of these...probably in this order.
Cardio doesn't make you fat. The 2 cheeseburgers you eat afterwards does that.
Bodybuilders "tend" to be more obsessive over their diet and macros. People that JUST do cardio are often untrained weekend warriors....easier for a novice to hop on the elliptical versus doing Rippetoe's 5x5 Stronglifts program or Wendler's 5x3x1 with all big compound lifts.
Correlation without causation.
There is such a thing as TOO MUCH cardio, but 99% of Americans ain't gotta worry about that. Distance runners can put in 50, 60, 70+ miles per week running, easily....