Show Related Posts of Specific Category Wordpress

Use following code to show  Related Posts of Specific Category in wordpress 
$categories = get_the_category($post->ID);
if ($categories) {
    $category_ids = array();
    foreach($categories as $individual_category) $category_ids[] = $individual_category->term_id;

    $args=array(
        'category__in' => $category_ids,
        'post__not_in' => array($post->ID),
        'showposts'=>5, // Number of related posts that will be shown.
        'caller_get_posts'=>1
    );
    $my_query = new wp_query($args);
    if( $my_query->have_posts() ) {
        echo '<h3>Related Posts</h3><ul>';
        while ($my_query->have_posts()) {
            $my_query->the_post();
        ?>
            <li><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_title(); ?></a></li>
        <?php
        }
        echo '</ul>';
    }
}