If you feel like you're not strong enough, you could try
hanging, using an [words=https://shop.mattersofsize.com/products/sizegenetics-penis-extender]extender[/words], [words=http://www.mattersofsize.com/forum/showthread.php?83577-Length-master-official-order-thread-now-shipping-06-16-2014!!!]
length master[/words], [words=http://www.mattersofsize.com/join-now.html]
power assist[/words], or
kettle bell v-stretches