1. Exercise
Physical activity can generally improve your posture, but core exercises are best. Your core includes muscles around your abdomen, back, and pelvis. 

2. Sit Up Straight
Trying to sit tall with your shoulders dropped is a good habit to get into if you work at a desk. You'll want to properly position your chair, documents, keyboard, monitor, and phone. 

3. Get Proper Nutrients

Calcium and Vitamin D are essential for strong bones and muscles, which helps prevent osteoporosis. Before starting any supplement, talk to your healthcare provider. 

4. Get Up and Move

As muscles tire, slouching, slumping, and other poor postures become more likely; this in turn puts extra pressure on the neck and back. In order to maintain a relaxed yet supported posture, change positions frequently. 

5. Perform Posture Checks
Becoming aware of posture and ergonomics at work, at home, and at play is a vital step towards instilling good posture and ergonomic techniques. Try to perform regular posture checks throughout the day to improve your posture and health. 

Source: Spine-Health.com & Foundation for Chiropractic Progress