I used to have anxiety when I started doing it but I think the key is to not judge or try and block away any feelings you're currently having. Just acknowledge them and let them go by focusing on something else, your breath or your heartbeat, even on things like the temperature in the room, the feeling of the chair or bed against your body. It's all about staying in the present moment, so try not to think about the past or the future just the present. Focusing on things like your breath keep you present. Maybe the guided ones on youtube aren't for you, but do try again even when you're not anxious.