I saw that someone mentioned jelqing earlier, and I feel obligated to give my input on that. I'm kind of ashamed to admit this, but I gave it a try a few months ago, and I still can't get a normal erection. :/ I did it a few times in one day, but never for more than a few minutes continuously. At the time, I didn't notice any obvious signs that I was causing damage. I definitely didn't feel even the slightest hint of pain, or I would've stopped immediately. But when I tried fapping later in the day, it simply went limp. Since then, it's been somewhat numb and doesn't really become erect. The most worrying part is that it seems there is really no cure for certain penile injuries. At this point, I'm hoping that I just have a nerve injury that will eventually heal, albeit very slowly. I can't vouch for whether or not this jelqing practice could really have any positive effect, but the risks certainly don't justify the potential gain. It's not fun to feel insecure about your body, but I don't think this jelqing nonsense helps.