a little serious
You know your life is getting a little bit more serious when you start having your own business card.
There's the added responsibilities, commitments and expectations to your life. No longer can you afford to have a relaxed life where you're free to do whatever you want based on the fancy of the moment but rather everything has to be planned and executed properly. Like the famous Uncle Ben once said, "With great powers comes great responsibilities".
I think I'll need to start depending on Google calendars instead of my slow functioning brain to keep track of all my meetings, schedule and responsibilities now. And perhaps buy a smartphone at the same time too.