If your marriage doesn't include fun activities, you need to re-group. Don't wait for retirement to start enjoying life. Make fun and play an essential part of your relationship, now. Make the time. Make time together a priority in your marriage.
Great fun takes thought and planning.
Be serious about setting aside time to be less serious. When you are out together, try to eliminate all distractions. Protect fun from conflict. Fun times aren't so much fun anymore when conflict erupts. Deal with important issues of your relationship in another meeting set aside for that purpose.