The Flash arms, legs, abs.

Do just one body part or all three if you're ambitious.

Scene takes place anywhere in Star Labs
          .....15 tricep pushups
          .....20 sumo squats
          .....20 oblique/side crunches each side

Barry uses his powers
          .....30 second plank
          .....15 backward leg lifts each side
          .....20 bicycles  

Tech explanation, or someone Does Science
          .....10 push ups
          .....20 jumping jacks
          .....10 straight leg lifts

Barry wears the Flash suit 
Scene takes place at Jitters
          .....15 lateral arm raises
          .....15 forward leg lifts each side
          .....10 reverse crunches

Scene takes place in the precinct 
Villain uses their powers
          .....20 bicep curls
          .....30 calf raises
          .....20 crunches

Character is awkward around character of the opposite sex 
Someone uses a villain's nickname
          .....15 shoulder presses
          .....30 second wall sit
          .....20 Russian twists