How do I add a date format to custom block output I have two custom block output fields that are date

    function my_three_upcoming_events() {
  $output = '';
  $now_events = views_get_view_result('schedule_list2');
  $upcoming_events = views_get_view_result('clone_of_now');
  $max_events = 3;

  $all_events = array_merge($now_events, $upcoming_events);
/*   print_r ('&lt;pre&gt;');
print_r ($all_events);
exit();
*/  for ($i=0,$z=$max_events;$i&lt;$z;$i++) {

    $node = node_load($all_events[$i]-&gt;nid);
    $output .='&lt;div&gt;' . l($node-&gt;title,'/node/'.$node-&gt;nid) . '&lt;/div&gt;';
    $output .='&lt;div&gt;' .($node-&gt;body[und][0][value]) . '&lt;/div&gt;';
    $output .='&lt;div&gt;' .($node-&gt;field_venue[und][0][value]) . '&lt;/div&gt;';
    $output .='&lt;div&gt;' .($node-&gt;field_session_start_date[und][0][value]) . '&lt;/div&gt;';
    $output .='&lt;div&gt;' .($node-&gt;field_session_start_date[und][0][value2]) . '&lt;/div&gt;';







  }


}


and they output like this

2014-04-18 15:15:00
2014-04-19 21:15:00

How can I change to one of the php date formats 

Thanks for any help on this
You should use date_format (Drupal function).