There is no instant fix for tight hips, chest, abdominals and quadriceps, but if you regularly stretch and try not to spend hours at a time in a seated position - you'll definitely notice a difference in the next few weeks. See the picture of the woman sitting? So wrong in many ways but I'll focus on posture!
I have drawn circles on the areas where her muscles are in contraction (chest, abdominals, hip flexors, shoulders). All the muscles in the
FRONT of the body. After work, she might go and do
BodyPump where she'll lift heavy chest weights, lunge and squat. Sound like some of us?
Pictured below are stretches that you can do in the gym and at home to extend and relieve postural tension. Try to engage the glutes (bum) to stabilise your hips and strengthen the back of your body.