How do you prevent a hernia? Are any exercises a risk?

You get older, and your tissue gets structurally weaker, and just has a hard time holding things in. You can’t really absolutely prevent getting them and still go about your daily routine. It’s just one of those things.

As @MyNewtBoobs mentioned you can’t really stop it from happening if you already have a structurally weak abdomen wall.
But you can prevent it from becoming a real problem by also wearing a good back brace that wraps completely around the abdomen when lifting and you should live with your knees and not your back.
Doing exercises to keep your core sturdy also helps.
And don’t do excessive lifting.
If something weighs enough that you can’t hold it up comfortably, than you should enlist the help of others so you put less strain on your abdomen.
Some people are actually born with a hernia and the hole or weak spot can close up with time,
and some don’t and may need surgery to close it up.
My son was born with a hernia around his belly button but it closed up on its own as he got older.

I have one now and it was caused due to a surgery. I need to have it repaired.

I’ve had two inguinal hernias. I think that I developed one of them from chopping wood. Weak fascia tissue is perhaps the biggest factor in contributing to inguinal hernias. You can build up the strength in all of your abdominal muscles but if your fascia is very weak then you will still be prone to developing inguinal hernias. Nevertheless I still make it a priority of mine to do abdominal exercises daily. My doctor informed me that if I develop another inguinal hernia then he will be installing a mesh screen inside of my abdomen to prevent a 4th hernia. I don’t want that for sure.

Also: yes pushing down too hard while generating a poop could cause an inguinal hernia.

Also: If you get a hernia, then see a doctor right away about it. An untreated abdominal hernia could quickly become a life threatening situation.

Hernias are typically caused by not stretching combined with doing strenuous exercise which you are not accustomed to doing. Lastly, they are sometimes caused by moving in unnatural ways.

Easiest way to prevent them is by easing into physical activity and warming up.