Question: Every time I go walking or hiking, I generally spend most of my time looking down to make sure I don't step on a snake or hole or dog poop. I don't do it consciously, it just happens. Obviously, I miss out on a lot of birds and small animals up in the trees and I'd like to see how other people cope with the urge to avoid obstacles and just enjoy their surroundings.

How can I go walking and hiking without constantly looking down?

Answer: 
The trick to be able memorize the immediate trail ahead of you and pick your footfalls several steps before you get to them.

It's the same as offroad driving. You can't see over your hood, and hanging out your window only lets you see one side of your vehicle. You have to memorize the features on the ground ahead and know where your wheels are so you can avoid those features when they disappear from view.

The same can be done while hiking. While you have your head up enjoying the scenery, make mental notes of the trail ahead, if you know where you're feet are, then you can learn to step over obstacles and avoid trip hazards without having to look down and watch your feet the whole time.
Ha ha. You can't. At least not off a leveled surface. I've struggled with this too. If I look down I miss the views; if I look up I trip. So I look ahead for a place to stop and enjoy. Then I march on, eyes on the rocks and detritus in the trail, until I reach my looky place.