Getting married and having kids. Even if you adopt. Some have said a marriage without children is self serving, which may be fine for many, but is counter to your aim of a purpose greater than you
telling someone the path to happiness is through marriage and kids is probably the dumbest advice imaginable. its basically a coin flip on whether or not it ruins your life and the data supports this.
No matter if the data supports it or not, all that your comment is telling me is that you don't have kids.