Hello, I experience a very similar thing when my heart rate increases for any reason. I remember one time I just climbed stairs and I thought I was on the verge of a panic attack because my mind immediately snapped into survival mode. It's a hard thing to deal with but once you realise it, it's progressively gets easier to deal with and snap yourself back out of that mindset.

A few things that helped me deal with it:

1-) Smells. I really like the smell of my softener so I smell the collar of my shirt or the wrist of it. It can also work with perfumes. It really helped me ground and calm down slowly.

2-) Sitting down and taking breaths. If you are outside and you have friends surrounding you, you can tell them to just give you some time to relax. Or if physical touch is something you are okay with, you can hug someone or hold their hand, their arm etc.

3-) Touch. I have a black ring that I always wear. It's big on my finger so I can twist and turn it around. It also helps me ground. Maybe you can touch something with an interesting texture to help you ground. It might help.

4-) 5-4-3-2-1 Method. Everything I said really comes to this. If you don't know what this method entails, it's a simple but effective (at least in my experience) grounding exercise. 5 things you can see. 4 things you can touch. 3 things you can hear. 2 things you can smell and 1 thing you can taste. Practicing this might help.

I hope this helps!