It takes a little bit of work. If you get gas at BP the cashier will gve you these cards(the Cashier gave me 13) its best to find a cashier that dosent really value their job as i think your only supposed to get 1 card for every 8$ worth of gas. anyways check it out ive already got 20$ free gas.
https://www.thankyoudays.com/
https://www.thankyoudays.com/