public function activate(User $user)
    {
        $user->is_activated = ! $user->is_activated;
        $user->save();

        if ($user->is_activated) {
            return $this->notifySuccess('User ' . $user->name . ' activated!');
        } else {
            return $this->notifySuccess('User ' . $user->name . ' deactivated!');
        }
    }