Im about to turn 20 and the past year my erections have noticeably been softer than previous years. its slightly embarrassing when im in the sack because i know i could be harder. ive been taking supplements (greentea extract, zinc, etc. ) thats supposably helps blood circulation all over the body. however i suspect it is my lack of exercise (and smoking hookah) the past 2 years that has driven down my testosterone level down to shit. what do you guys recommend?