Using myself for example. Due to lots of fun jelqing, lots of fun cock flexing, lots of delightful masturbation as well as lots of sexy fun bum clenching, my whole area is becoming like a muscle, strong and firm.
I can't over state that all of these self pleasures take time, yes! time time time! Dont get discouraged! Young or older, learn how to milk stroke your cock, you can do it, it's way fun!
Cock flexing at first can be awkward, so, do a little flexing and if it becomes un fun, just jack off, now, we can all do that, right? Next time, in bed or in the tub, try again. After a while you will start to get it right! And oh boy, its so cool getting all hard, laying on your back and flexing that lovely thing. I do it every morning in my nice warm bed, first thing, while my cock is firm and pouty. And the sweet little bonus wiping is very yummy. My cock drips like a crying babby, don't you just love a nice wet cock?
Jelquing, learn how, learn your own style of milk stroking your shaft. Jelquing is the best thing I ever did for my cock, but, it takes time, please, for your own good, learn these things. The main thing jelqing does is bring more expanding blood into your cock which in turn allows the cock to hold more blood, thus a bigger, harder more bulging erection! It is really true and sooooooo fun.
Buttock clenching, as in squeezing your bum and pushing your pubic mound upward like you do just when your going to shoot your milk on your tummy. Squeeze and flex your cock. On your back with legs slightly apart, flex your cock, flex, flex, flex, it will become so fun and self pleasuring after time and practise. The result of all this cock play and cock exercise will be a whole pubic area that is strong and firm with a nice flat tummy and strong pubic mound. Also, this will make your cock stand out more and look bigger and even get bigger. What is happening in part is, your perenium becomes more pronounced and forward, thus, more cock to play with and show off in the showers or at the beach. My cock realy stands out even when soft, my sack, everything, is reacting to all this attention and exercise and firming up and out.
Eat well, exercise, and stay healthy or get healthy. Learn to be proud of your cock, big or small, hairy or bald, cut or uncut. Become a master at cock fun and exercise.