lazy-related-posts.php

<?php
$related_query = new WP_Query( array(
	'post_type' => get_post_type(),
	'category__in' => wp_get_post_categories( get_the_ID() ),
	'post__not_in' => array( get_the_ID() ),
	'posts_per_page' => 3,
	'orderby' => 'date',
) );
?>

<?php if ( $related_query->have_posts() ) : ?>
	<ul>
		<?php while ( $related_query->have_posts() ) : $related_query->the_post(); ?>
			<li>
				<a href='<?php the_permalink(); ?>'><?php the_title(); ?></a>
			</li>
		<?php endwhile; ?>
	</ul>
	<?php wp_reset_postdata(); ?>
<?php endif; ?>