I wish people wouldn't fling around the word "immature" as if they themselves lacked immaturity and the recipient didn't. (Most of the time when one accuses another of a character flaw, they themselves have that same flaw, and are therefore hypocrites.) One of the problems with society today is that everyone seems to expect the other guy to be mature, but no one is in mutual agreement as to what the definition of maturity actually is. I can infer that today's version of maturity is generally acting like a Vulcan, and anything resembling impulsive emotions is immature, but I think we all know deep down how very wrong that is.
I can therefore conclude that maturity is of no real value in today's Western world, and therefore I do away with any attempts on my part to achieve it, and focus instead on being a good person.
You know, love and kindness and turning the other cheek and all that.
I do know a couple of things maturity isn't: being inconsiderate and self-centered. But I don't see what having a bit of passion has to do with anything...