Stand or sit upright with your spine neutral
Pull your shoulder blades slightly down and together
Tighten the muscles along both sides of your spine
Squeeze your upper back by drawing your elbows back
Arch your lower back gently by tilting your pelvis forward
Contract your lats by pulling your shoulders down and away from your ears
Hold the flex for a few seconds
Relax slowly
Repeat the flex several times
Practice in front of a mirror to check muscle engagement
Use light resistance like a band or dumbbells if needed
Breathe normally while flexing
Avoid shrugging your shoulders
Avoid over-arching your lower back