I am 30 year old and i have lot of pain in my knee joints, i spend most of my time in office on chair. what practise i follow to avoid pain in future?

Anterior knee pain: Pain is due to increased constant pressure in front of your knees. You should stand up periodically at work and just walk around. At home and in the gym, you should work on increasing the strength of the part of your quadriceps muscle inside your thigh by lifting (with or without weight) your leg while keeping your toes pointed outward. Also when seated try to keep your knees straight.

Knee pain: In addition to other good HT advice you received, be sure to see your doctor. If there is a condition such as arthritis she/he will help you w/that. A more balanced lifestyle may also help, e.g., a personal trainer at a gym and a healthy low-inflammatory diet. Peace and good health.