OK, this really does not appropriately answer your question, but a month before I turned 30, I was really freaking out. I was so stupid. I felt like I had very little to learn and all that turning 30 was symbolic of was just another decade.
A good friend of mine talked me off that ledge. She told me that we learn more and more every year and that 30 is not the be all and end all of maturity or knowledge. I was just being ridiculous.
Life was good for me at 29, after a rough decade already, so that is what shaped that outlook for me. Now, I am finally mature enough to realize that what I know now pales in comparison to what I will know in another ten years, and so on and so on.
To better answer your question, about me, post 30 is that I realize that all too many friendships change and that some are worth the follow through, and others are just better left in the past, and maybe will find their way back.