public function stopRunningActivity()
	{
		$runningActivity = $this->selectRunningActivity();

		// There is no running activity...
		if (!($runningActivity instanceof ActivityEntity)) {
			return false;
		}

		$nowObj = new \DateTime('now');
		$nowStr = $nowObj->format(\DateTime::RFC3339);
		$activityId = $runningActivity->getActivityId();

		$stmt = $this->pdo->prepare(
			"UPDATE `$this->tableName` SET `Stopped` = :stopped WHERE `ActivityId` = :activityId "
		);
		$stmt->bindParam(':stopped', $nowStr, \PDO::PARAM_STR);
		$stmt->bindParam(':activityId', $activityId, \PDO::PARAM_INT);
		$res = $stmt->execute();

		return $res;
	}