Which ones have you done? I'm married now (and have been for quite some time...) but Let's see how I'm doing...
1. Travel alone. Yup. Summer between my freshman and sophmore years of college I loaded a sleeping bag and some clothes in my car and road tripped for a month. Slept in the car most of the time, showered at truck stops... cheap travel.

I still love to travel, but always with my wife. It's a lot more fun.
2. Wallow in the ache of a broken heart. Good lord, what person
hasn't done this?
3. Spend a weekend with a married couple your age. Never did this, really, that I can think of, until after my first marriage. Maybe I should have...
4. DonÂ’t come home all night. Oh my. How many times??
5. Stand up for a cause you care about. Still do this...
6. Have a real adventure. Another one of those things that you should still do when you're
not single. Me? Traveled all over Europe. Took Sue to England, rented a Porsche 911 for tour of southern England, and married her on the battlements of Amberley Castle. Hit 169MPH in my TA on the open highway at the Silver State Classic. Run both the most scenic and most difficult Jeep trails in the state. Swam with a hawksbill turtle 100+ feet down. Adventures are, if anything, more important after you're married.
7. Learn how to take care of yourself. I like to think I can do this. I've lived alone, and my mother made certain I could cook (edibly, at least) and sew on a button.
8. Buy something hugely impractical just because you love it. I do this more now than I did when I was single, for purely financial reasons.
9. Develop a hobby. Another one of those things that is at least as important after you're married. People need interests other than each other. The adventures you have can easily lead to hobbies you'll enjoy forever.
10. Be completely, utterly, wholly single for at least three months. Done this too. Being married to Sue is a much better option (and no, she doesn't read this forum, so I'm not saying that to stay out of trouble..

)