I want to keep a journal, but I'm afraid someone will find it...?

Hi, I've usually kept my journal on my computer, but I hear that it can be more empowering to do it in a notebook or something. Anyways, I want to start writing my journal in a notebook, but I'm afraid that other people will find it. I'm especially afraid that people will find out information that would either really upset them, or really embarr me. I don't feel like writing a journal in which I will only tell half of the truth, because then it would be kind of pointless. What should I do?