Either you were born with a tendency to have weak tissues at the site of the hernia, or you have developed a weakness such as from a previous surgery incision. Hernias are very common such that effectively if you develop one it is almost “one of those things” and the rest of your body otherwise and muscles can be very strong and robust (often athletes get hernias). In the groin on each side of the pubis everyone has a ‘weak spot’ for anatomical reasons – in men the blood vessels and a tube to the testicles need to pass through the muscles to the scrotum, and in females a ligament holding the uterus passes through it. At the umbilicus (belly button) is the site where the umbilical cord was connected to your mother and which needs to ‘close over’ after your birth so not to have a hernia from birth (it can still close over after birth but remain a weak spot for a hernia to occur later in life). During surgery the abdominal wall muscles are repaired with stitches and often mesh. The bulk of the healing at the incision occurs over a 6 week period. Other sites of hernia can also occur and potentially for both of these reasons.