I am 23 year old male, slim about 52 KG and 5.6 ft tall. I feel I am very weak and having very less physical strength. I cannot run more than 10 steps and cannot do more than 10 squats at a stretch, as I feel my legs are locked. After running a while, I cannot take a step forward until I calm done for few seconds. I feel the same while climbing the stairs. I cannot do any repetitive task fast, such as rotating my arms, tightening a screw or any such daily chores which need such repetitive action. I couldn t play any sport which needs running since my school time. What could be the reason for this and how do I overcome. Kindly advice.