Anxiety is one of those things you do not want to get roots. So for peace-of-mind, you prepare as much as is possible, cover the worstcase scenario, and have distractions to not let your mind run wild.
As an example. Early morning driving is something that normally sets my anxiety levels to DEFCON 5 (aka highest possible). Which is not a baseless fear, as I've crapped myself while driving, and had more close calls then I can count. So, I do what I can do for peace-of-mind before leaving the house in the early morning: I give myself extra time to sit on the toilet, and do so one last time just before leaving just to make sure I don't have to poop. I say to myself "Okay bowels, I know you despise me, know my feeling for you is the same, but we gotta get to work lol!." I have an emergency kit available in the trunk of the car for worstcase scenarios, and I know where some reliable bathrooms will be along the route for peace-of-mind. When driving, I'll have the radio on to distract my crazy, runaway mind from its bathroom worries. I'll put on NPR and have something interesting to listen to, or put on music and sing *badly* along.
It's one of those things where once that anxiety-train gains a full head of steam, it becomes an unstoppable force, and your worries become a self-fulfilling prophecy. I end up getting so darn worried, with sweaty palms, heart racing, and gurgling gut, that stopping to attempt a poop is a more-or-less forgone conclusion. However, keep myself distracted, and not give anxiety roots and I do just fine.
Just now reading this response, nodding to every single word, while sitting on the toilet, getting myself mentally and physically ready to tackle taking the kids to school in the car! Roll on the next hour.