"Just be yourself." I hear this advice given via media and passing conversation, especially among teens. I'm not quite sure what it means.
Looking at it from one point of view, it might mean, "I really love you and think you are great. Don't get discouraged by those who are trying to cut you down. You do so many wonderful things that only you can do in your special way. You don't need to change to fit some arbitrary standard." This is sweet, reassuring, and hopefully true.
Looking at it from another point of view, it might mean, "Do whatever you want to do." This is wrong advice when speaking about serious matters, no matter what.
If I ever advised someone to "Just be yourself," it was a long, long, time ago. Now I would be more clear. I would say, "Just be your best self. God made you one-of-a-kind and has important plans for you. Be sure to share your time and talents well. Know right from wrong and keep striving for what is good."