Not display post meta if empty

Use in this way-

<strong>
<?php 
$duration_in_seconds = get_post_meta( get_the_ID(), 'wpscript_duration', true );

if( '' != $duration_in_seconds && 0 != $duration_in_seconds ) {
    $minutes = floor($duration_in_seconds / 60);
    $seconds = $duration_in_seconds - (60 * $minutes);
    echo $minutes;
    echo " MIN";
}

?> 
</strong>