My response is a lot like lily's. I try to get 25 grams. When I first started I thought it would be hard. When I just looked at my nutridiary report for the last 10 weeks, I've averaged 39 g a day!
So, it hasn't turned out to be hard, once I started making good choices.
I too, eat lots of whole grain foods (oatmeal, whole grain breads, etc), lots of fruit and veg. I put beans in a lot of the meals I make and they're great for fiber.