Buffel-Horing works for me. Just like Tank101 mentioned, you need to be aroused, then you will feel it work. The only side effect is a light headaches sometimes, not all the time. Available on takealot, read the reviews.
www.takealot.com/buffel-horing-erection-booster-15-capsules
Remember, "You don't need running shoes to run, but boy, do they help!"