How to improve a guy sex stamina?

I believed i'm having this problem during a long term tiredness course of sleep late and stop exercise for almost 3 years. Beginning of first year still ok, second year start getting weak... third year(this year) the beginning of my sex life disaster, it won't stay long. is it becoz of my lifestyle? and I love my wife.

How to improve a guy sex stamina?
I'm sure that the lack of sleep and exercise are not helping. But I know that another cause could be from extreme stress or depression. It may not have anything to do with you being attracted to your wife, but just the things that are going on in your life. If you have had anything that has really upset you (loss of a loved one, loss of your job, etc. - feeling like things are out of your control), that may be a cause. You might want see a doctor, if you can't figure out what is causing it. My mother said that a guy not staying hard long comes with age, but I'm not sure about that.
Reply:It might sound silly, but you can try some herbal remedies, such as "horny goat weed", or "ginkogaloba" both available in pills.
Reply:if its abt that u dont have a desire toward ur wife any more , u can take a multivitamins that contain zinc , if its abt pre mature ejaculation , u can take a drug called confidu .
Reply:OK try this if you just want to last in bed. My husband and i do this and it works. the stop and go is what Sue says on her show(cable and don't know the channel) We do this all the time. Use foreplay at the best time. Let her get pleased a bit then have her please you have sex and stop and start all over again its fun and can last for hours but I do want to tell you. You can lose your errection at times and you of all people should know that playing can keep it. Now another thing don't stay hard for more then 4 hours its not safe for you. You can try penis rings as well with this and they will help out a bit as well they don't stop you from a orgasm its help to prolong is all it will do. If your penis gets cold from the penis ring take it off right away its to tight or your blood flow has stopped all together it will happen so don't get one too lose and one not to tight that will make it cold.