If you’re looking to isolate the muscles in your booty, stretch your legs, zero in on your core — and maybe have a moment of gratitude, as well — look no further than Bailey Brown’s Pilates workouts.

With the rhythms of fall ushering in a fresh start, many of us are reimagining our wellness routines—ditching pricey gym memberships for the ease and comfort of at-home workouts on YouTube. These days ...