What Matmacwc said is correct. Tolerating G's is more about having good AGSM technique than anything else. Second most important is having an ATAGS (the new g-suit). Third is being physically fit.
Being tall, short, fat, or skinny does not affect your G-tolerance enough to concern you. Also, the only times you pull 8-9 Gs are during BFM & ACM. And even then, it's only for 6-9 seconds at a time (unless you're messing it up).
Bottomline: Stay generally physically fit. Don't skip leg day, but don't stop upperbody workouts as well. And for your own health, you should be running 1-2 times a week.
https://distractify-media-prod.cdn.bingo/1558806-980x.jpg