If you have time before you do it, you can practice. I've done this for meetings and presentations that I anticipate will be difficult. I start by imagining what someone else would do ("how would my competent friends handle themselves in a meeting like this?") and then try on different versions of myself, if it's not immediately obvious what a braver version of myself would do. (I often have that problem.) It's like what Brienne describes but over a longer period of time, so you can take advantage of habit formation. Then, if you have what you'll say and how you'll say it well rehearsed (not memorized, but rehearsed), it's easier to go into the difficult situation sort of on autopilot. You can keep Brienne's technique in your back pocket if the autopilot fails.
The downside of rehearsal in your head is that you might find yourself dwelling on all the horrible things that could happen. This is usually where my mind goes if I let it because it's easy to let the models I have of other people run amok and show me all the worst possibilities that I might have to face. You have to just rehearse the part you know you own and not spend too long imagining in vivid detail what happens next, besides what is useful for preparation (like what beoShaffer suggests and similar practical plans). I hope it works out for you and you'll let us know how it goes!
Make an effort to look at other peoples' bodies and note who appears more fit.
If you think of "fitness buffs" as being a special clique, then noticing other potential members of the clique and feeling like you belong to something bigger than yourself can reinforce your "fitness buff" identity. However, this technique can be very counterproductive. Women in the US and elsewhere are often socialized to compete with each other on the basis of appearance already, so noticing fitter women is already something that we do with not necessarily very positive results.
Actually, I try to keep appearance out my mind when I exercise because I've had issues with body dysmorphic disorder. Instead, I identify as someone who's into, say, urban cycling. Now I notice when other people are carrying a bike helmet with them when they're in a shop, for instance. I feel like a part of a group, and this feeling of identity encourages me to keep biking.
By the way, the idea that you can tell how fit or healthy someone is just by looking at them isn't correct. Some thin, healthy-looking people don't exercise, and some people who are overweight are actually quite healthy according to other measures of fitness, so I'd shy away from using appearance as a proxy for fitness.
Sure, but who claims/acts as if isolated facts do produce a science?
Science classes, especially before high school level, are often taught as though science is just a collection facts about trees or dinosaurs or whatever. Anyone who hasn't had the benefit of a good science program in their school might continue to think that science is just experiments to generate facts.
The Art of Learning: A Journey in the Pursuit of Excellence by Josh Waitzkin is the memoir of a chess child prodigy who later became a Tai Chi Chuan world champion. It's organized around his advice on developing the good habits of thought that he discovered when he was training for chess. But they are applicable to many domains: he makes the argument that the habits that made him excel at chess were also what made him a world-class competitor in Tai Chi Chuan.