girls how should I sit ( my girlfriend said about my posture) how exactly should i sit and stand?

Question

I kinda put this in the wrong catogree on accident sorry

Answer 1

How to Improve Your Posture

1. Know what good posture is believed to be. Most people think that to "stand up straight" means tensing your back to heave your chest 'in and up', and pulling your head back in to your chest. This is not so. The spine has two natural curves that you need to maintain called the 'double C' or 'S' curves, these are the curves found from the base of your head to your shoulders and the curve from the upper back to the base of the spine. When standing straight up, make sure that your weight is evenly distributed on your feet. You might feel like you are leaning forward, and look stupid, but you don't.
2. Using a mirror, align your ears, shoulder, and hips. Proper alignment places your ears loosely above your shoulders, above your hips. Again, these points make a straight line, but the spine itself curves in a slight 'S'. You'll find that this doesn't hurt at all. If you do experience pain, look at your side view in a mirror to see if you're forcing your back into an unnatural position. If so, stop it!
3. Do exercises that strengthen the muscles across your upper back and shoulders. These do not have to be strenuous! Try the following, with or without hand weights:
Align your ears over your shoulders. Raise both arms straight up, alongside your ears. Remember to keep your ears aligned! Bend forearms toward shoulders to touch your shoulder blades. Do 10 repetitions with both arms, then alternate 10 reps for each arm singularly.
Align ears with shoulders. Raise both arms out to sides at shoulder length. Hold for a slow count of ten. Slowly lower arms to sides, counting ten as you lower. Slowly raise arms back to shoulder height, counting to ten as you raise arms. Do ten reps, constantly checking your alignment! If ten reps are too many to start, do as many as you can. You should at least feel a slight fatigue in the shoulder muscles.
Be a penguin. While you wait for a web page to load, toast to pop, or the microwave to beep, place elbows at your side, and touch your shoulders with your hands. Keeping your hands on your shoulders, and your ears aligned, raise both elbows (count one, two) and lower them back to your waist (count one, two). Do as many reps as your wait allows. You'll be surprised how much exercise fits into 30 seconds.
4. Do stretches. This can greatly help if you find that you have a sore back or neck after a while.
Tilt (stretch) your head in all four directions over your shoulders (forward, back, left, right), and gently massage your neck. Avoid rolling in a circle, as it may cause further strain.
On your hands and knees, curl your back upwards, like a cat, and then the opposite. Think about being able to place a bowl in the hollow of your back.
5. Repeat the exercises a few times each day. Doing them in the morning helps your body stretch out the muscle lethargy of sleep, and periodically throughout the day helps raise your energy level without a heavy workout.

Sitting
Sit in an office chair.
Align your back with the back of the office chair. Avoid slouching or leaning forward, especially when tired from sitting in the office chair for long periods. Keep your shoulders straight.
Flex your arms at a 75 to 90 degree angle at the elbows. You may have to adjust the office chair.
Make sure your neck, back, and heels are all aligned.
Keep both feet flat on the floor. If there's a problem with feet reaching the floor comfortably, a footrest can be used along with the office chair

Standing
Stand with weight mostly on the balls of the feet, not with weight on the heels. Avoid locking your knees.
Keep feet slightly apart, about shoulder-width
Let arms hang naturally down the sides of the body
Tuck the chin in a little to keep the head level. Be sure the head is square on top of the neck and spine, not pushed out forward
Stand straight and tall, with shoulders upright
Stand against a wall with shoulders and bottom touching wall. In this position, the back of the head should also touch the wall - if it does not, the head is carried to far forward (anterior head carriage).

Walking
Keep the head up and eyes looking straight ahead. Avoid pushing your head forward
Keep shoulders properly aligned with the rest of the body

Driving
Sit with the back firmly against the seat for proper back support. The seat should be a proper distance from the pedals and steering wheel to avoid leaning forward or reaching
The headrest should support the middle of the head to keep it upright. Tilt the headrest forward if possible to make sure that the head-to-headrest distance is not more than four inches.

Carrying Objects
Always bend at the knees, not the waist
Use the large leg and stomach muscles for lifting, not the lower back
If necessary, get a supportive belt to help maintain good posture while lifting
When carrying what a heavy or large object, keep it close to the chest
If carrying something with one arm, switch arms frequently
When carrying a backpack or purse, keep it as light as possible, and balance the weight on both sides as much as possible, or alternate from side to side
When carrying a backpack, avoid leaning forward or rounding the shoulders. If the weight feels like too much, consider using a rolling backpack with wheels.

Sleeping
A relatively firm mattress is generally best for proper back support, although individual preference is very important
Sleeping on the side or back is usually more comfortable for the back than sleeping on the stomach
Use a pillow to provide proper support and alignment for the head and shoulders
Consider putting a rolled-up towel under the neck and a pillow under the knees to better support the spine
If sleeping on the side, a relatively flat pillow placed between the legs will help keep the spine aligned and straight.

You can have someone tape a giant X on your back from one shoulder to the opposite hip. Then put a straight line of tape across your shoulders closing the top of the X. Wear this during the day, to help retrain your back. This works really well if you hold shoulders back before taping, use wide non stretch tape and ideally change tape each day
Don't tighten up your muscles when you are assuming a straight posture. It will only stress the joints and muscles themselves and this affects the skeleton, therefore your posture and even the way you move and breathe. Try to eventually relax into it but if you experience back pains, stop it! You are probably causing unnecessary muscle tension. It is important to differentiate between back pains, and muscle exhaustion. Since the correct posture is foreign, the muscles needed to maintain that posture might not be strong enough yet. A guideline for this is that if it strains you to breath, realign your posture. Let the breath guide you, it needs to feel good! It can take weeks to strengthen the muscle imbalances and this is very tough work, but worth it in the end.
If your head is hanging, you can't be properly aligned. Keep your head at the level that allows you to look directly ahead without having to turn your eyes up. If you cannot do this without feeling tension in your neck, this means you are causing unnecessary muscle tension.
A great side benefit of keeping your head straight, and your ears/shoulders/hips aligned is an improvement in your self-esteem and attitude. If you walk with your head up, you appear more confident, and feel more confident, which improves your attitude and mood, making it easier to walk with your head up.
Try these steps to get in alignment: push your shoulders forward, then bring them straight up, then bring them straight back, then bring them staight down. Feel good? If your shoulders feel slightly stiff or tense you may have unnecessary muscle tension.
If you feel pain, especially back pain when trying to attain 'correct' posture you could consider learning the Alexander Technique with a qualified teacher , this is a proven learning technique which helps drop unneccessary muscle tension, regain natural posture and also adds a quality of ease to the way you move and work.
If you need help remembering to keep your posture, think of a unique object or color. Everytime you think of that object, check your posture.

Do not keep doing exercises until you feel pain or more than a slight fatigue! This will not get you there faster. Instead it will frustrate you and make you less likely to continue the exercises. If you can only do 3 reps, do 3 reps when you get up, and 3 after breakfast, and three just before you leave the house. Tomorrow or the next day, you'll be able to do 4. Then 7, then 10.
Anyone with back, neck, or pelvic injuries should not attempt to correct their posture themselves. This could further damage the body. Contact your Doctor or call an Alexander Technique Teacher before trying to tamper with your alignment.

Answer 2

ok i have a few recommendations
posture is the basic starting point for everything you do in your life.
get the book "The New Rules of Posture" by Mary Bond.
Start doing
Alexander Technique
Feldenkrais
Yoga
Pilates
or just about any form of dance

You can't just automatically make your posture different. Like becoming a pro athlete, it's a matter of awareness and practice.