How to save money and not be tempted to spend it.?

This summer I have been getting loads of money... Yet, every time I have some I am tempted to go to Kohl's and buy something... So basically now I have spent $12 last week and I spent it all on clothes on sale.. And recently I have earned more money, how can I keep myself from being tempted into spending it. I have it in my wallet in a secret slot but yet even then spending it is still on my mind... What should I do? (I don't own any piggy banks that have to be broken to get the money)...