Behind every perfectly tailored “Bridgerton” costume and ad for Lululemon leggings lies the work of fit models, the unsung heroes who help designers create clothes that actually work on real bodies.

It’s clear that the shirtless, perfectly chiseled fitness model on the magazine cover at your local grocery store is in peak shape, but it’s less clear how he got into that shape in the first place.

If you have a penchant for holding poses—both in the yoga studio and in front of the camera—you might be interested in becoming a model for athleisure retailer Lululemon. This guide can help you ...