You really need to call your doctor or pharmacist about this one - blood pressure meds affect how your body responds to exercise, and the timing can matter depending on your specific situation and how your body reacts. Generally, most people take lisinopril once daily at the same time each day (often morning), so if that's when you're supposed to take it, taking it before the gym is fine, but some folks do better taking it after to avoid dizziness during a workout. Since you've been on it for six months, your next appointment is the perfect time to ask, or just call the clinic now - it's a quick question and they know your full medical picture way better than anyone online can.