I am 83 and had the same problem as I started my daily routine at 13 I would recommend to give your hand and/or pillow a L o n g break
Different things can help. One may sound kind of like not how you picture sex with your wife, but while having sex in the very start of it, begin thinking about other things. Yes, not too sexy but may give you longer time before ejaculation. There is also something called the pause squeeze technique. It strengthens your pelvic floor muscles so you'd have more control This article tells you how to do it. (copy and paste) https://www.mayoclinic.org/diseases-conditions/premature-ejaculation/diagnosis-treatment/drc-20354905 I WILL say that the article suggests getting testosterone tested to be sure there isn't a problem there. So, you might want to consider that but doubt there is an issue. It just covers all your bases. Something else if you don't have issues 'getting' erections is to masturbate an hour before sex. Men often last longer when actually having sex when premature ejaculation is an issue. Your future wife will love that you are so excited by her but understand that you'd like to last for enough time that she an receive pleasure so just work on it.
I don't know what you mean by "not long", but the average time for a man to "last" - from the start of intercourse to orgasm - is about 5 minutes. That's the average - that means some go faster, some longer. Some studies put this at 2-3 minutes. Premature ejaculation is defined as ejaculating before 60 seconds.
Women take longer - about 13 minutes, and most - about 80% don't orgasm from penetration alone.
So foreplay is important for a woman, and for you.
It's hard for me to be more specific for you. I don't know what your heart disease is, if you have any risks from vigorous activity, if you are on any medications, or if your "not long" is actually not long, or just some standard you think you should meet.