Avoid sitting Cross legged.
Quadriceps Exercises- Lie straight, make a towel role and put it under the knee, press the keen against the role, hold it for 20 secs. Repeat 20 times twice a day. This will help relieve some pain.
Core Strengthening Exercise- Straight Leg Raised With Toes Turned Outward, repeat 10 times, twice a day.
Hams Stretching- lie straight, take the leg up, pull the feet towards yourself, with a elastic tube or normal belt. repeat 10 times, twice a day.
Sports Taping- stretch the tape from both ends and apply on the affected area
Contrast Fomentation (Hot and Cold).
With this details it is very difficult to diagnose you but at the age 25 having knee pain is due to trauma or lack of flexibility or stiffness in the knee joint so that take hot water fermentation or perform light knee stretching. For yoga take help of expert and for any pathology in knee kindly show to nearby orthopaedic specialist.