You will have NO control of getting an erection.
Talk to your friend's Father-in-Law. There is the opposite side of taking something that is not required you could develop a dependency on the Viagra. Since you would then think, subconsciously that since there is no ordinary 3 hour erection that something is wrong and then need to take the drug to develop and maintain your erection. Ron Jeremy, the porn-star has stated he refuses to take the drug just for that reason.
Viagra enable men to erect, up to fur hours. It a oral medicine but its important to use it according to prescription, its is highly recommended to use vigara without doctor's opinion. Misusage of dose can lead a person towards serious disease. So it's good to consult your doctor first .
if you are a healthy male and is using viagra, sooner or later you body will become immune to it that it wont work as efficiently as before and you manhood head will always be pissing on your toes.( meaning it wont get up.)