Gyms in Bashak Shahir (Istanbul)

Hello everyone! My wife and I have just moved to Istanbul and are living in Bashak Shahir, in an area close to Olimpiyat Stadium. I am struggling to find a gym in this area. We found one called Mac Fitness at the Mall of Istanbul; however, they do not accept cash or debit cards, only credit cards. I do not use credit cards so this is a problem. I hope it is not an issue common in Turkey. Does anyone have any suggestions for gyms in the area?

Regards,

Nicolai