Even cybernetically-enhanced supersoldiers need to work out to stay buff. For a man of few words you need to be able to walk the walk as well as talk the talk and the Master Chief workout is good 'ol plain, solid military fitness. You need strong.
Skyfall Workout, from neila rey. Really neat website with themed workouts (based on TV shows/movies), programs or 90 days), challenges, and other helpful workout tips. Good excuse to watch part of the show/movie while you're doing the workout!
This website has a lot of workouts laid out so that if you want an idea of what to do, you can grab one and go. The filter at the bottom of the page lets you select the type of workout (abs, strength, HIIT, etc) if you'd like to filter it down.