How difficult will it be to obtain a PhD in Physics in university?

I’ve decide to return to school after finally figuring out my passion in life. It turns out I am extremely interested in physics and how things work so I wish to learn more and make it my profession. Are there any people out there who could tell me how difficult it will be? I realize it won’t be a walk in the park and I’m looking at about 10 years of school. I just want to hear from people who have gone through it who can tell me what I can expect from this study. Thanks!