I know how the OP feels.
I recently borrowed a friend's mid/high-end Novarra mtn bike to take out on a local single track trail at a state park nearby. I usually ride out to the same lake on my touring bike, but getting out in the woods on a mountain bike let me experience the same park from a completely new level.
The ride through the woods kicked my ass. I got exhausted, dirty, and came close to hurting myself a few times. But the whole experience was sublime. It's hectic and loud when moving and peacefully silent when stopped. There's also no idiots yelling out the windows of a passing trucks - a definite plus.
Mountain biking though the woods is a whole different animal from riding on paved roads --- a whole new set of hazards and skill requirements present themselves, and it can be very challenging and intimidating to those of us who are used to just riding roads.
I definitely want to try it again soon.