Background info: I'm around 5'5 and weigh around 143lbs. I'm not that active but I'm not unfit where I get tired after the first few minutes of a run.
Whenever I try do push ups I can only do around 4 before my shoulders start to hurt. I can hold a plank for around a minute. Anyone know why this might be happening and how I can increase the amount of push ups I can do?