Everyone's info is well-meaning, but probably not related to what Donuel is talking about. If it's "just below the navel" and in the midline, then it's not an inguinal hernia, which is the most common kind and the one most people tell their stories about. From his description I suspect he may have something called a ventral or epiploic hernia, also known as an epiplocele. It often can cause intense pain (unlike most inguinal hernias, unless they're incarcerated), and is notoriously difficult to diagnose. It's caused by a small amount of fatty tissue from the omentum protruding through a defect in the midline of the abdominal wall. It should be fairly easy to cure it surgically, and I wouldn't expect a very prolonged or difficult convalescence. But I'm not a surgeon, and my diagnosis may be wrong. Best bet would be to ask your surgeon.

Aloha,
Mark