public function post($data = [])
 {
     if (empty($data)) {
         throw new Exception('Some data is needed to be posted.');
     } else {
         $activity = new ActivityModel();
         if (array_key_exists('user_id', $data)) {
             $activity->setUserId($data['user_id']);
         }
         if (array_key_exists('exercise_name', $data)) {
             $activity->setExerciseName($data['exercise_name']);
         }
         if (array_key_exists('exercise_duration', $data)) {
             $activity->setExerciseDuration($data['exercise_duration']);
         }
         if (array_key_exists('exercise_calories', $data)) {
             $activity->setExerciseCalories($data['exercise_calories']);
         }
         if (array_key_exists('exercise_distance', $data)) {
             $activity->setExerciseDistance($data['exercise_distance']);
         }
         if (array_key_exists('exercise_timestamp', $data)) {
             $activity->setExerciseTimestamp($data['exercise_timestamp']);
         }
         if ($activity->save()) {
             return true;
         } else {
             return false;
         }
     }
 }