exchange/app/Notification.php

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class Notification extends Model
{
    protected $fillable = ['detail','user_id','is_read'];
    protected $appends = ['time_interval'];

    public function getTimeIntervalAttribute()
	{
		$created_time = $this->created_at;

		date_default_timezone_set('Asia/Kuala_Lumpur'); //Change as per your default time
        $str = strtotime($created_time);
        $today = strtotime(date('Y-m-d H:i:s'));

        // It returns the time difference in Seconds...
        $time_differnce = $today-$str;

        // To Calculate the time difference in Years...
        $years = 60*60*24*365;

        // To Calculate the time difference in Months...
        $months = 60*60*24*30;

        // To Calculate the time difference in Days...
        $days = 60*60*24;

        // To Calculate the time difference in Hours...
        $hours = 60*60;

        // To Calculate the time difference in Minutes...
        $minutes = 60;

        if(intval($time_differnce/$years) > 1)
        {
            return intval($time_differnce/$years)." years ago";
        }else if(intval($time_differnce/$years) > 0)
        {
            return intval($time_differnce/$years)." year ago";
        }else if(intval($time_differnce/$months) > 1)
        {
            return intval($time_differnce/$months)." months ago";
        }else if(intval(($time_differnce/$months)) > 0)
        {
            return intval(($time_differnce/$months))." month ago";
        }else if(intval(($time_differnce/$days)) > 1)
        {
            return intval(($time_differnce/$days))." days ago";
        }else if (intval(($time_differnce/$days)) > 0) 
        {
            return intval(($time_differnce/$days))." day ago";
        }else if (intval(($time_differnce/$hours)) > 1) 
        {
            return intval(($time_differnce/$hours))." hours ago";
        }else if (intval(($time_differnce/$hours)) > 0) 
        {
            return intval(($time_differnce/$hours))." hour ago";
        }else if (intval(($time_differnce/$minutes)) > 1) 
        {
            return intval(($time_differnce/$minutes))." minutes ago";
        }else if (intval(($time_differnce/$minutes)) > 0) 
        {
            return intval(($time_differnce/$minutes))." minute ago";
        }else if (intval(($time_differnce)) > 1) 
        {
            return intval(($time_differnce))." seconds ago";
        }else
        {
            return "few seconds ago";
        }
	}

}