add_filter('get_the_time', 'my_get_the_time', 100, 3 );

function my_get_the_time($the_time, $d, $post){
    return findTimeAgo( get_post_time('U', true, $post) );
}

function findTimeAgo( $past ) {

    // creates the "time ago" string. This always starts with an "about..."
    $timeAgo = "";

    // finds the time difference
    $timeDifference = time() - $past;

    // less than 29secs
    if($timeDifference <= 29) {
      $timeAgo = "less than a minute";
    }
    // more than 29secs and less than 1min29secss
    else if($timeDifference > 29 && $timeDifference <= 89) {
      $timeAgo = "1 minute";
    }
    // between 1min30secs and 44mins29secs
    else if($timeDifference > 89 &&
      $timeDifference <= ((MINUTE_IN_SECONDS * 44) + 29)
    ) {
      $minutes = floor($timeDifference / MINUTE_IN_SECONDS);
      $timeAgo = $minutes." minutes";
    }
    // between 44mins30secs and 1hour29mins29secs
    else if(
      $timeDifference > ((MINUTE_IN_SECONDS * 44) + 29)
      &&
      $timeDifference < ((MINUTE_IN_SECONDS * 89) + 29)
    ) {
      $timeAgo = "about 1 hour";
    }
    // between 1hour29mins30secs and 23hours59mins29secs
    else if(
      $timeDifference > (
        (MINUTE_IN_SECONDS * 89) +
        29
      )
      &&
      $timeDifference <= (
        (HOUR_IN_SECONDS * 23) +
        (MINUTE_IN_SECONDS * 59) +
        29
      )
    ) {
      $hours = floor($timeDifference / HOUR_IN_SECONDS);
      $timeAgo = $hours." hours";
    }
    // between 23hours59mins30secs and 47hours59mins29secs
    else if(
      $timeDifference > (
        (HOUR_IN_SECONDS * 23) +
        (MINUTE_IN_SECONDS * 59) +
        29
      )
      &&
      $timeDifference <= (
        (HOUR_IN_SECONDS * 47) +
        (MINUTE_IN_SECONDS * 59) +
        29
      )
    ) {
      $timeAgo = "1 day";
    }
    // between 47hours59mins30secs and 29days23hours59mins29secs
    else if(
      $timeDifference > (
        (HOUR_IN_SECONDS * 47) +
        (MINUTE_IN_SECONDS * 59) +
        29
      )
      &&
      $timeDifference <= (
        (DAY_IN_SECONDS * 29) +
        (HOUR_IN_SECONDS * 23) +
        (MINUTE_IN_SECONDS * 59) +
        29
      )
    ) {
      $days = floor($timeDifference / DAY_IN_SECONDS);
      $timeAgo = $days." days";
    }
    // between 29days23hours59mins30secs and 59days23hours59mins29secs
    else if(
      $timeDifference > (
        (DAY_IN_SECONDS * 29) +
        (HOUR_IN_SECONDS * 23) +
        (MINUTE_IN_SECONDS * 59) +
        29
      )
      &&
      $timeDifference <= (
        (DAY_IN_SECONDS * 59) +
        (HOUR_IN_SECONDS * 23) +
        (MINUTE_IN_SECONDS * 59) +
        29
      )
    ) {
      $timeAgo = "about 1 month";
    }
    // between 59days23hours59mins30secs and 1year (minus 1sec)
    else if(
      $timeDifference > (
        (DAY_IN_SECONDS * 59) +
        (HOUR_IN_SECONDS * 23) +
        (MINUTE_IN_SECONDS * 59) +
        29
      )
      &&
      $timeDifference < YEAR_IN_SECONDS
    ) {
      $months = round($timeDifference / MONTH_IN_SECONDS);
      // if months is 1, then set it to 2, because we are "past" 1 month
      if($months == 1) {
        $months = 2;
      }

      $timeAgo = $months." months";
    }
    // between 1year and 2years (minus 1sec)
    else if(
      $timeDifference >= YEAR_IN_SECONDS
      &&
      $timeDifference < (YEAR_IN_SECONDS * 2)
    ) {
      $timeAgo = "about 1 year";
    }
    // 2years or more
    else {
      $years = floor($timeDifference / YEAR_IN_SECONDS);
      $timeAgo = "over ".$years." years";
    }

    return $timeAgo." ago";
}