In 2006, bestselling author of Exercising the Penis, Aaron Kemmer, did a survey with 1,000 men who exercised their penis. The results showed that those who exercised for at least three months:

• Gained an average one inch in length
• Gained an average 1/2 inch in girth
• Increased their penis size by nearly 50 percent on average in terms of volume
• Gained up to three inches in length and two inches in girth or more
• Reported stronger and harder erections