<?php $paged = get_query_var( 'page' ) ? get_query_var( 'page' ) : 1; ?>
<?php $loop = new WP_Query( array( 'post_type' => 'business-challenges', 'paged' => $paged, 'posts_per_page' => 1) ); ?>

<?php while ( $loop->have_posts() ) : $loop->the_post(); ?>
...
<?php endwhile; wp_reset_query();  ?>


and outside of that, near page header:

<a href="<?php echo get_next_posts_page_link(); ?>" class="page-menu-next"><span class="icon-right"></span></a>