Sleeping on the Ground

I went camping and the main thing I'm still pondering over is sleeping.
In a tent.
On the ground.

When did sleeping on the ground become something I'd think about?
More to the point: When did it become noticeably uncomfortable?
And can it be reversed? Is it just because I, as I am inclined to (want to) believe, am not used to it?
It never bothered me 20 years ago and I don't want to believe that it's the 20 years, by themselves, that matter.
It's not like I haven't camped in 20 years, but I guess bedroll-with-a-few-extra-blankets-because-we're-car-camping is not sleeping-bag-on-ground-camping.

I will suck it up and get over it.

Noteably: It has been 20 years since I've camped alone.
I like the solitude and the quiet. I like it so much I will be doing more of it. I'm setting up my backpack for my next trip so I can hike in and ditch the car-camping.