/**
  * Responds to requests to GET /exercises/{slug}
  */
 public function getShow($slug)
 {
     $exercise = Exercise::with('images')->where('slug', $slug)->first();
     $recommended_exercises = Exercise::where('primary_muscle_id', $exercise->primary_muscle_id)->where('id', '<>', $exercise->id)->orderBy('name')->take(10)->get();
     if (!$exercise) {
         return view('errors.404');
     }
     return view('exercises.show', ['exercise' => $exercise, 'recommended_exercises' => $recommended_exercises]);
 }