I guess I don't mean that I could be more like them and less like myself, but be happy like they are and carefree like they are; have the emotions they have. Sorry for the confusion.
And I can see it in ISFJs too. I need to work on the perfectionist thing (Type 1 here). I also think being selfish can be a good thing sometimes. It is important to take care of yourself before you take care of others.
Namaste--
Pull a coin out of your pocket. Go ahead...we're waiting. Got it? Good!
Now look at that coin. What do you see? Two sides? Exactly...two sides...heads and tails.
Can you split that coin and still have one undamaged and complete coin? Of course not.
That coin is like all personality types. Every type has two sides, or two set of qualities...good and bad. It is obvious to you, living inside of your ISTJ skin what your good and bad qualities are...but you tend to focus on the bad and feel like you aren't such a good person. That's kindof how we do it.
Now, you see some of the qualities in these other people. Qualities that you admire. What you aren't noticing so much is the negatives of being that type of person.
Remember our coin? You get the whole coin, or you get nothing. You can't keep the head side of the coin and leave the tail side, and still be able to use the coin. You also don't get to cherry pick the various attributes of personality types. This isn't a cafe, where you can pick what you want. So if you want to be an ISTP, you gotta take the good with the bad. And believe me, every type has it's demons to fight.
Now, shift directions a bit.
Happiness comes from within. If you embrace who you are, shortcomings and all, and work to overcome those shortcomings to the best of your ability, then happiness and contentment is not far off. You are who you are for a reason. You bring abilities to your network of friends and family that others don't bring. They need you to be like you are. Sure, there are times that it ain't so great, but it all works out for the best when we contribute our part and let the others contribute their part.
HTH