Pro runner Emma Grace Hurley had a few doubts and questions heading into last weekend’s Chicago Marathon , her first 26.2-mile race.

Would she and her pacer, Caleb Kerr, end up on separate sides of the road at the race start? How would she manage to grab a bottle from an aid-station table on a crowded course? And how fatigued, exactly, would her legs feel after mile 20 ?

Despite the unknowns—and the significant media attention focused on her marathon debut—Hurley was far more excited and curious than nervous. That’s largely because she and her coach, Andrew Begley, built up to this moment slowly and methodically.

Ever since the pair joined forces at the Atlanta Track Club in 2021, they knew she would eventually take on the marathon. But early on in her pro career, they decided her odds of long-term success would be higher if they didn’t rush the process.…