public static function updateFromRequest($exercise, $request)
 {
     $thumbnail = $request->file('thumbnail');
     if ($thumbnail) {
         $thumbnail_url = ExerciseImage::uploadThumbnail($thumbnail);
         $exercise->thumbnail_url = $thumbnail_url;
     }
     $exercise->name = $request->input('name');
     $exercise->type_id = $request->input('type_id');
     $exercise->mechanic_id = $request->input('mechanic_id');
     $exercise->force_id = $request->input('force_id');
     $exercise->difficulty_id = $request->input('difficulty_id');
     $exercise->primary_muscle_id = $request->input('primary_muscle_id');
     $exercise->secondary_muscle_id = $request->input('secondary_muscle_id');
     $exercise->description = $request->input('description');
     $exercise->save();
 }