If you think that your penis is too small, be sure to measure it accurately. Even if it is shorter than average, it's important to place the size of your penis in context and ask yourself why it is causing you such distress. It sometimes helps to speak with a psychologist who can help you sort through your feelings and provide the perspective you need.
Do a little Jelquing, or try Male Extra (more information available HERE) in order to get extra blood flowing to your organ. This is optional, but will help speed up the process. The key to most muscle and tissue recovery/growth is making sure the cells are getting oxygenated and receive the proper nutrients. Blood carries all of that to the tissue, so the more, the better.
Eat watermelon. It's not an herb, but it has properties that might help increase the size and duration of erections in a similar way arginine. Watermelon contains an amino acid called citrulline, which gets converted into arginine and leads to the dilation of blood vessels. The fact that watermelon contains citrulline is a relatively new finding, so no studies have been conducted to find out how well it really works or how much watermelon you'd have to eat to see the benefits. However, since watermelon is considered a superfood when it comes to men's health, you can't go wrong by eating plenty of it while it's in season.
After warming up process, you will move to the lubrication exercise, which is one of the most important ways to increase your penis size naturally. In fact, you can find out a lot of lubricants to enlarge penis size, but the usual method is to use petroleum-based or water-based lubricants. I recommend lubricant oil, which includes botanical extracts, vitamin complexes, and antioxidants that go straight into the tissues of the penis for fast, targeted, immediate results. Remember that water-base lubricant can be dried out fast, therefore, you should put the lubricant during the exercise.
The vacuum pump. This is a cylinder that sucks out air. You stick your penis in and the resulting vacuum draws extra blood into it, making it erect and a little bigger. You then clamp off the penis with a tight ring -- like a tourniquet -- to keep the blood from leaking back into your body. What are the drawbacks? The effect only lasts as long as you have the ring on. Using it for more than 20 to 30 minutes can cause tissue damage. This is sometimes used as a treatment for erectile dysfunction, but has not been proven to actually increase the size of the penis.