Think of a mantra you can repeat in your head over and over again.

being in public can be exhausting. something that has helped me has been to try and make myself feel as safe and comfortable as possible. like wearing clothes that feel comfortable or bringing some things in my bag from home like chapstick, water, something to fidget with, headphones, a sketchbook, etc. and when I'm out I try to remind myself that it's okay to take breaks. like sitting in the bathroom for a few minutes to take deep breathes and have a second alone.