I am twenty one and cant do any aerobic activity for a span longer than thirty secs!

Patient: I am 21 years old. I experience rather alarming symptoms for my ageI am easily tired. I have a horrid stamina. Almost instant shortness of breath while cycling skipping rope or running.I don’t even weigh that much in respect to my height. I feel body ache even after 9 hours of sleep.Please, what can i do to improve?