Here's a good article on Hall from Steve Sisson who coached her for 3 years at Texas.
Sounds like she is someone who is very dedicated to her craft. Great to see it payoff with such a big breakthrough.
Prior to her final outdoor season, Marielle was an extremely talented, committed distance runner who’d had a solid career, showing flashes of excellence, but unable to close out races on the biggest stages. In training, she was an absolute beast. Her track sessions indicated an incredible talent balanced with an unmatched work ethic. I know this because I was Marielle’s coach at Texas for three years. In the time I coached her, no one worked harder or was more consistent than Marielle. She came prepared for every single practice with a focus and drive unlike I have ever seen. But it never translated when it counted…until Saturday.
...No one works harder than Marielle Hall; absolutely no one.