I got one too after having my daughter (she's my only child). Mine actually happened right when I gave birth--it felt like a knife slid me open from side to side across my stomache--but my Ob/gyn said her job was done and that I would have to bring it up with my regular doctor.
I did. It took him 2.5 years to finally send me to a surgeon who poked me in a spot next to my belly button and asked, "does that hurt?" I just about ended up passed out on the floor!
It took until I was suffering from severe, sharp pains that almost made me black out before my doctor got serious about it. It happened once in downtown morning rush-hour traffic. I said that's enough; I want it fixed.
The problem I had was the exact area of the hernia; my regular doctor couldn't "find it." The surgeon said it depended on how you were presenting--sitting, laying down, standing (I was standing for him) and the approximate spot of where the hernia would be.
By the time the surgeon got in there and finally plugged up the hole/put my colon back where it should be, it was a pretty big hole to plug up. He had to put a piece of plastic in there to make sure the fixture would stay.
One problem that can result (besides pain) is that the longer there is a hole/tear in the barrier between the colon and the rest of the body, the more you can suffer from Leaky Gut/Dysbiosis, which isn't a good thing. It can lead to food allergies and food intolerances, or it can make any you have worse or even lead to more of them.
If you're done having children, I'd urge you to get the hernia taken care of. (Unless the hernia is severe, they usually like to wait until you're all done having children, so they don't have to worry about the reconstruction surgery being torn apart.) However, if you have an umbilical hernia and get pregnant, you can have a pretty intense/painful pregnancy. And very rarely, the hernia can rupture, which is then a serious, life or death situation that results in immediate surgery.
I tried to do strengthening/core abdominal muscle exercises after I had my daughter/up to the hernia surgery when she was 2.5 years old, but the exercises aggravated the hernia and I wasn't able to do them. Even now, with the hernia fixed, the piece of plastic in there makes doing certain abdominal exercises hard.
I also started having problems with gas/bloating/being very uncomfortable when I ate or drank liquids (Water made me bloat up REALLY bad).
As one poster stated, strangulation is a very, very bad thing. And she's right; hernias do NOT go away on their own. She's also right; a hernia is your colon sticking out of the intestinal wall. Personally, I had a lot of problems with mine so fixing it was a no-brainer. But I would have fixed it even if the problems weren't that bad simply because I didn't want to have to worry about it all the time and not know what was going on inside my body/what might happen because of the weak intestinal wall.