Build a Better Butt in 22 Days With This Glute Workout Program Athlean-X's Jeff Cavaliere shares his plan for better glutes and hamstrings in under a month. May 25, 2021 Simply put, Athlean-X founder Jeff Cavaliere C.S.C.S., does not want you to have a flat (or weak) ass. He's previously shared his 4 favorite exercises to strengthen your weak glute muscles. And now, he's sharing the ultimate 22-day glute and hamstring workout plan that will give you a strong, pronounced backside. "Everything you need to build your butt and kickstart a better looking backside is here in a mapped out plan," says Cavaliere.