There is an exercise that can help improve your sexual stamina. Guys this exercises are called kegel exercises. This exercise can help boost stamina and can also help improve your erection and bladder control as well. But It will not help to increase your joystick LOL.

I have been doing the exercise for quite sometime and my stamina has improved. When you first start doing the exercise you will not see immediate results. When I started doing them I did not see results at first but I kept on doing them for 3-4 weeks and i saw some improvements.

So what you do is you clench your pc muscle. Your pc muscle is your pelvic floor muscle that provides support to your bladder,urethra and bowel.It basically helps keep your organs in place. You can find the pc muscle when you are urinating. When urinating stop halfway,The muscle that holds that urination is your pc muscle.

Ok enough explanation. Let's get straight to it.
You have to clench your pc muscle for 10 seconds then release and do it again 30 to 40 times.
Make sure you target the pc muscles. While doing it don't tighten your stomach, buttocks or thighs and don't hold your breath when doing it,breathe normally.

You can do it standing up or sitting down.
Women can also benefit from it as well. the benefits are bladder control and great orgasms.