Add previous / post links to single posts

functions.php

// add previous / next posts to single posts
// change fl_post_bottom_meta_open to the hook that is appropriate to your theme. Genesis would use genesis_before_comments as the hook
add_action( 'fl_post_bottom_meta_open', 'eo_prev_next_post_nav' );
function eo_prev_next_post_nav() {
  
	if ( is_single() ) { ?>
 
		<div class="navi-previous-next clear clearfix">
	            <div class="navi-previous navi-item"> <?php 	
		    	$prevPost = get_previous_post();
			$prevthumbnail = get_the_post_thumbnail($prevPost->ID, 'medium'); ?>
		       	<p class="navi-icon"><?php previous_post_link('%link', '&larr; <span class="navi-title">Previous Article</span>');?></p>
		       	<div class="navi-post-content">
		  		<?php previous_post_link('%link', $prevthumbnail); ?>
		  		<?php previous_post_link('%link', '%title'); ?>
		  	</div>
	            </div>
	
	            <div class="navi-next navi-item"> <?php
	                $nextPost = get_next_post();
	                $nextthumbnail = get_the_post_thumbnail($nextPost->ID, 'medium'); ?>
	                <p class="navi-icon"><?php next_post_link('%link', '<span class="navi-title">Next Article</span> &rarr;'); ?></p>
	                <div class="navi-post-content">
	                	<?php next_post_link('%link', $nextthumbnail); ?>
	                	<?php next_post_link('%link', '%title'); ?>
	                </div>
	            </div>
	        </div>
 
	<?php }
 
}