I understand your problem.
Usually a persons lasting time in sex is. Hardly 5-15 mins and that totally depends upon lifestyles. My apologies for getting personal but I need to help you in all possible ways.
Lasting for.long time in bed not includes the penetration and ejaculation but also the foreplay and women could be satisfied with foreplay before starting the proper sex. Foreplay helps in buying time and also helps in making your sex more enjoyable. If you are not lasting for too long then try out different positions that you and your wife likes. Discuss before going having sex regarding your wife favourite sex positions and ask her in which way she likes it to be.
Knowing your wives likes will help you perform well and while having sex you should only think about your wife and ways to satisfy her and erase everything that is there in your mind.
Start your action slowly and increase the speed as time progresses and act according to your wife want you to be.
Foreplay helps in arousal of sexual desire in both of you.
To increase your endurance you need to start working out that is jogging for 20 mins and you may swim. These really helps you in lasting long. You need to take your stress out of your mind while you are with your wife.