"Just be yourself"

Have you ever been given this advice, nodded your head and then sat there and wondered I'm not sure what that means? The last time someone said that to me it was a friend of mine who was giving some advice after observing me train a client. When he said this to me it nearly brought me to tears. He said just be yourself and I remember thinking I don't even know who that is. I know I am a husband, a son and a man but beyond that I feel lost. The things that used to excite me no longer do or do so a lot less than they used to. I no longer have a passion for anything but I know that I want to find that passion for something and I'm not sure where to begin. I recently heard on a podcast I listen to the guest describe the host as the the person who is most true to their own self as anyone they have ever met. As I move on I think that would be a great place to start to be described as being true to myself once I find out who that guy is.