You must read "Penis Enlargement Bible" by John Collins, get the electronic format (PDF) @ https://www.getpebible.com - The reason why this penis enlargement exercise program is the best is because the whole process of growth is based on two pillars: mechanical one & biochemical, the other penis enlargement programs focus only on exercises making them less effective. Exercising your penis alone can damage your health for good.
The main goal of the book is to learn you how to get nutrient-rich blood and oxygen into your penis as much as possible which can help you gain the natural male enhancement. This nutrient-rich blood flow will support the cells in your penis to enlarge and repair quickly. Thence, just like during puberty, the new cells will be created.
The "2-step" method of The Penis Enlargement Bible works on a principle where biochemical reacts with receptors in your penis which were put there so that during the puberty, your penis would gradually grow. The 2nd step is making the enlarging process happen faster by performing exercises. The growth happens and your penis can take more blood, resulting in a bigger, thicker and much more powerful penis.
I gained about 0.9 inch in girth and 2.4 inch in length (erect) in 10 weeks by following this program, this book has changed my life. I also have better control over my erections and I last a lot longer. I hope this helps, I once was in your shoes and I know how it feels.